I was trying for the first time to read data from a file, a .txt file. Below is my code:
Level::ReadStream(std::fstream data)
{
bool write = false;
char* p = data.tellg();
while(!data.eof())
{
int i = 0, j = 0;
if(&p == '[')
{
write == true;
}
if(write == true)
{
mapX[i] = p;
mapY[j] = p;
}
if(&p == '/n')
{
i++;
j++;
}
else
{
i++;
}
*p++
}
};
void Level::SetMapSize(std::fstream data)
{
int* p = data.tellg();
int sizeX = 0;
int sizeY = 0;
while(!data.eof())
{
if(&p != '[' && &p != ']' && &p != '\n')
{
sizeX++;
}
else if(&p != '\n')
{
sizeY++;
}
}
mapX.resize(sizeX);
mapY.resize(sizeY);
std::cout << sizeX << '\n' << sizeY;
};
The goal of these two functions are to:
1- read all the chars in the file and, if the current character is not a bracket, add it to an index map(X, Y), then increase the counter so the next non-bracket value will be put in the correct index.
2- read all the file and, as before, count the non-bracket values, so it can make mapX and mapY the correct size.
However, it's not working, and I got these errors:
C:\...\Level.cpp|58|warning: multi-character character constant|
c:\...\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\bits\ios_base.h|790|error: 'std::ios_base::ios_base(const std::ios_base&)' is private|
c:\...\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\iosfwd|47|error: within this context|
c:...\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\iosfwd|87|note: synthesized method 'std::basic_ios<char, std::char_traits<char> >::basic_ios(const std::basic_ios<char, std::char_traits<char> >&)' first required here |
c:...\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\streambuf|770|error: 'std::basic_streambuf<_CharT, _Traits>::basic_streambuf(const std::basic_streambuf<_CharT, _Traits>&) [with _CharT = char, _Traits = std::char_traits<char>]' is private|
c:...\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\iosfwd|78|error: within this context|
c:...\mingw\bin\..\lib\gcc\mingw32\4.4.1\include\c++\iosfwd|87|note: synthesized method 'std::basic_filebuf<char, std::char_traits<char> >::basic_filebuf(const std::basic_filebuf<char, std::char_traits<char> >&)' first required here |
C:...\Level.cpp||In constructor 'Level::Level()':|
C:...\Level.cpp|24|note: synthesized method 'std::basic_fstream<char, std::char_traits<char> >::basic_fstream(const std::basic_fstream<char, std::char_traits<char> >&)' first required here |
C:...\Level.cpp|24|error: initializing argument 1 of 'void Level::SetMapSize(std::fstream)'|
C:...\Level.cpp|29|error: 'cout' was not declared in this scope|
C:...\Level.cpp|38|error: ISO C++ forbids declaration of 'ReadStream' with no type|
C:...\Level.cpp|38|error: prototype for 'int Level::ReadStream(std::fstream)' does not match any in class 'Level'|
C :...\Level.cpp|17|error: candidate is: void Level::ReadStream(std::fstream)|
C:...\Level.cpp||In member function 'void Level::SetMapSize(std::fstream)':|
C:...\Level.cpp|75|error: invalid conversion from 'std::streamoff' to 'int*'|
C:...\Level.cpp|81|error: ISO C++ forbids comparison between pointer and integer|
C:...\Level.cpp|81|error: ISO C++ forbids comparison between pointer and integer|
C:...\Level.cpp|81|error: ISO C++ forbids comparison between pointer and integer|
C:...\Level.cpp|86|error: ISO C++ forbids comparison between pointer and integer|
C:...\Level.cpp|95|error: 'cout' is not a member of 'std'|
||=== Build finished: 15 errors, 1 warnings ===|
Can anyone help?
EDIT: Ok, I changed everything. My new code is:
void Level::ReadStream()
{
long p = textData.tellg();
int counter = 0;
int i = 0;
int j = 0;
char ch;
while(p != textData.eof())
{
textData.seekg(counter);
textData >> ch;
if(ch != '[' && ch != ']')
{
mapX[i] = ch;
mapY[j] = ch;
i++;
if(ch == '\n')
{
i = 0;
j++;
}
}
counter++;
p = textData.tellg();
}
};
with mapX and mapY being 5 int long. Now it compiles, but hangs and crashes. I don't see why... Is there anyone that can help me?
It's \n not /n! That should clear some errors.
Also, you can't just take the pointer from tellg -- it returns the position, not the pointer to the position!
Basically try to read up on IO in C++, maybe start with this question:
How to read from a file char by char in C++?
Related
I have this basic multi tool program which goal is to complete four functions on a file that contains some strings.. take a string, for example, take a line and put it in uppercase.
I get that it's not perfect yet, but i need to understand why my char* and char** are doing some mess.
thanks a lot for your time
#include <iostream> //to use enter and exit
#include <cstring>
#include <string>
#include <fstream> //to use files
using namespace std;
/*--------------------------FONCTION PART-----------------------------------*/
//define one fonction for each transformation
//FONCTION 1
void fonctionu (char* argv){
char pattern = argv[2];
char file = argv[3];
fstream data(file, ios::in);
if (data){
string line;
while (getline (data ,line)){
unsigned found = line.find(pattern);
if (found != string::npos) {
for (int i = 0; line[i]!='\0'; i++) {
if(line[i] >= 'a' && line[i] <= 'z') {
line[i] = line[i] - (32);// (ASCII)
cout<<line[i];
}} }
if (found == string::npos) {
for (int i = 0; line[i]!='\0'; i++) {
cout<<line[i];
}}}}}
//FONCTION 2
void fonctiond( char* argv){ //remove line with xyz
char pattern = argv[2];
char file = argv[3];
fstream data(file, ios::in);
if (data){
string line;
while (getline (data ,line)){
unsigned found = line.find(pattern); //as a reminder argv[2] is the pattern (warning : it need to be an unsigned to compare two unsigned)
if (found != string::npos) {
//delete the line of the file when there is the pattern
cout<<'\0'; }
if (found == string::npos){
for (int i = 0; line[i]!='\0'; i++) {
cout<< line[i];
}}}}}
//FONCTION 3
void fonctionc( char* argv){
char pattern = argv[2];
char file = argv[3];
fstream data(file, ios::in);
if (data ){
string line;
while (getline (data ,line)){
unsigned found = line.find(pattern); //as a reminder argv[2] is the pattern
if (found != string::npos) {
for (int i = 0; line[i]!='\0'; i++) {
cout<< "\033[31m"<< line[i]; //the line will be red
}
}
if (found == string::npos){
for (int i = 0; line[i]!='\0'; i++) {
cout<< line[i];
}}}}}
//FONCTION 4
//replace the pattern xyz by abc
void fonctions ( char* argv){
char pattern = argv[2];
char file = argv[3];
fstream data(file, ios::in);
if (data ){
string line;
while (getline (data ,line)){
unsigned found = line.find(pattern);
if (found != string::npos) {
for (int i = 0; line[i]!='\0'; i++) {
if(line[i] >= 'a' && line[i] <= 'z') {
line[i] = line[i] - (97); // (ASCII) //we creat a shift that allow to make the x became a 'a' and the y a 'b'...etc
cout<<line[i];}}
}
if (found == string::npos) {
for (int i = 0; line[i]!='\0'; i++) {
cout<<line[i];
}}}}}
/*--------------------------MAIN PART---------------------------------------*/
int main(char* argv){
// ipsacs : argv[0]
//option :
string a = argv[1]; //string ! to compare line 103,108 and 112
// pattern : argv[2];
//file : argv[3];
if (argv[1]=='\0' || argv[2]=='\0'){
cout <<"ERROR"<<'\n';}
if (a == "u"){
char fonctionu (argv);}
if (a== "d"){
char fonctiond(argv);}
if (a == "c"){
char fonctionc(argv);}
if (a == "s"){
char fonctions(argv);}
return 0;
}
/*--------------------------TEST PART--------------------------------------*/
/*
pour compiler : g++ -Wall ipsacs.cpp -o ipsacs
./ipsacs u xyz foo //how the program would receive arguments, basically
Le programme ne renvoie rien.
*/
here is the compiling log:
main.cpp:22:30: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
fstream data(file, ios::in);
^
In file included from main.cpp:8:0:
/usr/include/c++/6/fstream:902:7: note: initializing argument 1 of ‘std::basic_fstream<_CharT, _Traits>::basic_fstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits; std::ios_base::openmode = std::_Ios_Openmode]’
basic_fstream(const char* __s,
^~~~~~~~~~~~~
main.cpp: In function ‘void fonctiond(char*)’:
main.cpp:46:29: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
fstream data(file, ios::in);
^
In file included from main.cpp:8:0:
/usr/include/c++/6/fstream:902:7: note: initializing argument 1 of ‘std::basic_fstream<_CharT, _Traits>::basic_fstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits; std::ios_base::openmode = std::_Ios_Openmode]’
basic_fstream(const char* __s,
^~~~~~~~~~~~~
main.cpp: In function ‘void fonctionc(char*)’:
main.cpp:66:29: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
fstream data(file, ios::in);
^
In file included from main.cpp:8:0:
/usr/include/c++/6/fstream:902:7: note: initializing argument 1 of ‘std::basic_fstream<_CharT, _Traits>::basic_fstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits; std::ios_base::openmode = std::_Ios_Openmode]’
basic_fstream(const char* __s,
^~~~~~~~~~~~~
main.cpp: In function ‘void fonctions(char*)’:
main.cpp:88:29: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
fstream data(file, ios::in);
^
In file included from main.cpp:8:0:
/usr/include/c++/6/fstream:902:7: note: initializing argument 1 of ‘std::basic_fstream<_CharT, _Traits>::basic_fstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits; std::ios_base::openmode = std::_Ios_Openmode]’
basic_fstream(const char* __s,
^~~~~~~~~~~~~
main.cpp: At global scope:
main.cpp:109:5: warning: first argument of ‘int main(char*)’ should be ‘int’ [-Wmain]
int main(char* argv){
^~~~
main.cpp:109:5: warning: ‘int main(char*)’ takes only zero or two arguments [-Wmain]
main.cpp: In function ‘int main(char*)’:
main.cpp:113:20: error: conversion from ‘char’ to non-scalar type ‘std::string {aka std::basic_string}’ requested
string a = argv[1]; //string ! to compare line 103,108 and 112
~~~~~~^
main.cpp:121:26: error: invalid conversion from ‘char*’ to ‘char’ [-fpermissive]
char fonctionu (argv);}
^
main.cpp:123:25: error: invalid conversion from ‘char*’ to ‘char’ [-fpermissive]
char fonctiond(argv);}
^
main.cpp:125:27: error: invalid conversion from ‘char*’ to ‘char’ [-fpermissive]
char fonctionc(argv);}
^
main.cpp:127:27: error: invalid conversion from ‘char*’ to ‘char’ [-fpermissive]
char fonctions(argv);}
^
A char * is a pointer to a memory address holding a character, and is often used for c-strings.
A char ** is a pointer to a memory address holding a pointer to a memory address holding a character, and is often used for arrays of c-strings.
Your main signature if not a valid form, since there's no form of main which takes in only a character pointer. The form you are most likely looking for is int main( int argc, int **argv ). This takes in two parameters: argc being the number of arguments passed to the program, and argv containing the parameters, as c-strings, passed to the program.
In the main method, you would generally ensure that argc is correct, i.e. you have the correct number of parameters passed into your function (note: it's always at least 1 will argv[0] being the program name).
std::string a = argv[1] is fine, and it will cause the string pointed to by argv to be converted to a string. When calling your functions, you have char functionu(argv);. You will want to remove the char from that line; effectively, the way it is written, you are trying to create a char variable named functionu which has an initial value of argv.
Each of your functions, instead of taking in a char * should take in a char ** instead, then when you have something like char file = argv[3];, you would want to change this to char *file = argv[3];, or std::string file = argv[3];
I need help fixing the following code, it is a c++ whitespace detector that uses different words to produce different outputs:
#include <algorithm>
#include <cctype>
#include <iostream>
#include <string>
using namespace std;
string Line;
string firstWord[99];
string secondWord[99];
int lineFunction(string line) {
string line[199];
for (int i = 0; i < line.length(); i++) {
while (isspace(line[i]) == false) {
firstWord += line[i];
}
secondWord += line[i];
}
}
int main() {
cin >> Line;
lineFunction(Line);
if (firstWord == "A") {
if (secondWord == "B") {
cout << "AB";
}
}
}
The expected result when I input A B (with a space) should be the letters AB (without a space, to test how it works) printed onto the screen, as a result of the if statements, but I am trying to make the output configurable. The errors that I receive when I try to run this are:
main.cpp: In function ‘int lineFunction(std::string)’:
main.cpp:12:20: error: declaration of ‘std::string line [199]’ shadows a parameter
string line[199];
^
main.cpp:13:30: error: request for member ‘length’ in ‘line’, which is of non-class type ‘std::string [199] {aka std::basic_string [199]}’
for (int i = 0; i < line.length(); i++) {
^~~~~~
main.cpp:14:31: error: no matching function for call to ‘isspace(std::string&)’
while (isspace(line[i]) == false) {
^
In file included from /usr/include/c++/6/cctype:42:0,
from main.cpp:2:
/usr/include/ctype.h:118:1: note: candidate: int isspace(int)
__exctype (isspace);
^
/usr/include/ctype.h:118:1: note: no known conversion for argument 1 from ‘std::string {aka std::basic_string}’ to ‘int’
In file included from /usr/include/c++/6/bits/basic_ios.h:37:0,
from /usr/include/c++/6/ios:44,
from /usr/include/c++/6/ostream:38,
from /usr/include/c++/6/iostream:39,
from main.cpp:3:
/usr/include/c++/6/bits/locale_facets.h:2565:5: note: candidate: template bool std::isspace(_CharT, const std::locale&)
isspace(_CharT __c, const locale& __loc)
^~~~~~~
/usr/include/c++/6/bits/locale_facets.h:2565:5: note: template argument deduction/substitution failed:
main.cpp:14:31: note: candidate expects 2 arguments, 1 provided
while (isspace(line[i]) == false) {
^
main.cpp:15:23: error: no match for ‘operator+=’ (operand types are ‘std::string [99] {aka std::basic_string [99]}’ and ‘std::string {aka std::basic_string}’)
firstWord += line[i];
~~~~~~~~~~^~~~~~~~~~
main.cpp:17:20: error: no match for ‘operator+=’ (operand types are ‘std::string [99] {aka std::basic_string [99]}’ and ‘std::string {aka std::basic_string}’)
secondWord += line[i];
~~~~~~~~~~~^~~~~~~~~~
main.cpp: In function ‘int main()’:
main.cpp:24:22: error: comparison between distinct pointer types ‘std::string* {aka std::basic_string*}’ and ‘const char*’ lacks a cast [-fpermissive]
if (firstWord == "A") {
^~~
main.cpp:25:27: error: comparison between distinct pointer types ‘std::string* {aka std::basic_string*}’ and ‘const char*’ lacks a cast [-fpermissive]
if (secondWord == "B") {
Here are some possible solutions to fix the errors.
#include <algorithm>
#include <cctype>
#include <iostream>
#include <string>
// don't use
// using namespace std;
// don't use global variables
// string Line;
// string firstWord[99]; you need strings, not arrays
// string secondWord[99];
// use references to return multiple values and no return value
// alternatively you could return a std::pair
void lineFunction(std::string line, std::string &firstWord, std::string &secondWord) {
// string line[199]; you don't need this variable
// line.length() return unsigned int so you should compare with unsigned int
// this whole loop makes no sense
// for (unsigned int i = 0; i < line.length(); i++) {
// this would result in a infinite loop
// while (isspace(line[i]) == false) {
// if (!std::isspace(line[i])) {
// firstWord += line[i];
// }
// secondWord += line[i];
// }
unsigned int i;
for (i = 0; i < line.length() && !std::isspace(line[i]); ++i) {
firstWord += line[i];
}
for (++i; i < line.length(); ++i) {
secondWord += line[i];
}
}
int main() {
std::string line;
// std::cin only reads until first whitespace
// std::cin >> line;
std::getline(std::cin, line);
std::string firstWord;
std::string secondWord;
lineFunction(line, firstWord, secondWord);
if (firstWord == "A" && secondWord == "B") {
std::cout << "AB";
}
}
I am reading in files from a repo and I am having trouble compiling the code. My github partner(using a mac) has no issue with the code but when I clone his repo, I get this issue.
Background info:
I recently moved into the Linux world and am running Elementary. Not sure if there could be an issue here since my other coding projects work, but it is background info.
error: no matching function for call to ‘std::basic_ifstream<char>::open(std::__cxx11::string&)’
infile.open(fullPath); // Open it up!
In file included from AVL.cpp:6:0:
/usr/include/c++/5/fstream:595:7: note: candidate: void std::basic_ifstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]
open(const char* __s, ios_base::openmode __mode = ios_base::in)
^
/usr/include/c++/5/fstream:595:7: note: no known conversion for argument 1 from ‘std::__cxx11::string {aka std::__cxx11::basic_string<char>}’ to ‘const char*’
Makefile:4: recipe for target 'main' failed
make: *** [main] Error 1
Here's my function:
void AVL::parseFileInsert(string fullPath) {
ifstream infile;
infile.open(fullPath); // Open it up!
std::string line;
char c;
string word = "";
//int jerry = 0;
while (getline(infile, line))
{
// Iterate through the string one letter at a time.
for (int i = 0; i < line.length(); i++) {
c = line.at(i); // Get a char from string
tolower(c);
// if it's NOT within these bounds, then it's not a character
if (! ( ( c >= 'a' && c <= 'z' ) || ( c >= 'A' && c <= 'Z' ) ) ) {
//if word is NOT an empty string, insert word into bst
if ( word != "" ) {
insert(word);
//jerry += 1;
//cout << jerry << endl;
//reset word string
word = "";
}
}
else {
word += string(1, c);
}
}
}
};
Anything is greatly appreciated!
The std::basic_fstream::open overload taking a const std::string & argument has been introduced in C++11. If the code compiles with one compiler but not another, it stands to reason that one compiler supports C++11 and the other doesn't (either by virtue of being too old, or by not specifying the C++ standard on the command line).
If you cannot switch to a C++11 compiler (or change the command line to enable C++11 support), you could simply change the line of code
infile.open(fullPath); // Open it up!
to
infile.open(fullPath.c_str()); // Open it up!
That doesn't change the semantics, with one exception: std::string supports embedded NUL characters, while the C-style string returned by c_str() does not. I'm not aware of a filesystem that allows embedded NUL characters in file/directory names, so that difference is of theoretical nature.
#include <iostream>
#include <string>
using namespace std;
float findSimilarityScore(string A, string B)
{
string C;
if (A.length() != B.length())
{
return -1;
}
if (A.length() == 0 and B.length() == 0)
{
return -1;
}
else
{
int i;
for (i = 0; A.length() - 1; i = i+1)
{
if (A[i] == B[i])
{
C.append(A[i]);
}
if (A[i] != B[i])
{
return 0;
}
}
cout << C << endl;
}
}
int main()
{
findSimilarityScore("DDS","DAS");
}
when i try to run my code, my IDE show this:
/home/ubuntu/workspace/hmwk4/hmwk4-1.cpp: In function ‘float findSimilarityScore(std::string, std::string)’:
/home/ubuntu/workspace/hmwk4/hmwk4-1.cpp:24:30: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
Why?
I want : if the first char in A is same to the first char in B, then add this char to the string C. if the second char in A is same to the second char in B, then add this char to the string C. And so on.
In the line
C.append(A[i]);
std::string::append has no overload that takes a single char. Use push_back instead:
C.push_back(A[i]);
This will fix your compilation error, but your function is still logically incorrect. It returns 0 the first time it finds any character that doesn't match between the two strings, and if the two strings are identical then it will invoke undefined behavior by reaching the end of a non-void function without returning a value.
string::append() with a single parameter is expecting a string argument, you are passing a single char. Try
C.append(1, A[i]);
Also, once you find a non-matching char, you return without printing the new string. Move the cout just before the return
if (A[i] != B[i])
{
cout << C << endl;
return 0;
}
And be sure to add a return at the end of your function in case you don't find any characters which are unequal.
I am having trouble with my code with something with arrays. I am getting the following errors
In function ‘int main(int, const char**)’:
75: error: cannot convert ‘char*’ to ‘char (*)[81]’ for argument ‘1’ ion(char (*)[81], OneItem*, int&, int&)’
In function ‘void parseInformation(char (*)[81], OneItem*, int&, in
164: error: ISO C++ forbids comparison between pointer and integer
166: error: incompatible types in assignment of ‘const char [2]’ to
169: error: ISO C++ forbids comparison between pointer and integer
174: error: ISO C++ forbids comparison between pointer and integer
174: error: ISO C++ forbids comparison between pointer and integer
176: error: invalid conversion from ‘char*’ to ‘char’
The code doesn't line up with the line numbers. I have tried multiple things googled some things still haven't found a solution.
const int MAX_CHARACTERS = 80;
const int MAX_INVENTORY = 12;
typedef char OneLine[MAX_CHARACTERS + 1];
struct OneItem
{
char product[MAX_CHARACTERS + 1];
int quantity;
float unitPrice;
float totalPrice;
};
int main( const int argc, const char* argv[] )
{
OneLine fileName;
ifstream inFile;
OneLine readLine;
OneItem inventory[MAX_INVENTORY];
int readLineIndex;
int structureCounter = 0;
int averageQuantity;
float averagePrice;
float averageTotalPrice;
displayIntroduction();
getFileName( argc, argv, fileName );
if (!inFile)
{
cout << "File not found: " << fileName << endl;
}
else
{
inFile.open(fileName);
while(!inFile.getline(readLine, MAX_CHARACTERS, '\n').eof())
{
if (structureCounter < MAX_INVENTORY)
{
parseInformation(readLine,inventory, readLineIndex, structureCounter);
}
}
void parseInformation(OneLine readLine[],OneItem inventory[], int & readLineIndex, int & structureCounter)
{
int tempIndex = 0;
int valueCounter = 0;
OneLine tempArray;
while(readLine[readLineIndex] != '\n')
{
tempArray = "\0";
while(readLine[readLineIndex] == ' ')
{
readLineIndex += 1;
}
while(readLine[readLineIndex] != ' ' && readLine[readLineIndex] != '\n')
{
tempArray[tempIndex] = readLine[readLineIndex];
tempIndex += 1;
readLineIndex += 1;
}
if(valueCounter == 0)
{
for(int i = 0; i <= strlen(tempArray); i++)
{
inventory[structureCounter].product[i] = tempArray[i];
}
valueCounter += 1;
}
else if(valueCounter == 1)
{
inventory[structureCounter].quantity = atoi(tempArray);
valueCounter += 1;
}
else
{
inventory[structureCounter].unitPrice = atof(tempArray);
structureCounter += 1;
}
}
return;
Your definition of parseInformation is wrong. It says that readLine should be an array of OneLine, but it only wants a single OneLine. It should be:
void parseInformation(OneLine readLine,OneItem inventory[], int & readLineIndex, int & structureCounter)
This is causing all the errors you're getting, because you're calling the function with a single OneLine, not an array. And inside the function you're comparing readLine[readLineIndex] with a character, which requires readLine to be an array of characters, not an array of OneLine.
The OneLine typedef makes this an array already, you didn't need to add [] to the parameter declaration.
As Barmar said you need to change first argument, but there is one more problem, here:
OneLine tempArray;
while(readLine[readLineIndex] != '\n')
{
tempArray = "\0";
You cannot make such assign. tempArray needs to be of type const char* or you need to make it this way:
tempArray[some_index] = '\0';