Why does this code print the char, without first character?? It says ocalhost instead of localhost. Grateful for help.
#include <winsock2.h>
#include <mysql/mysql.h>
#include <iostream>
#include <windows.h>
#include <fstream>
using namespace std;
int main () {
int b = 0;
char * pch;
int stringLength = 0;
char textRead[50];
ifstream infile("config.ini", ios::in | ios::binary);
if(!infile) {
cout << "ERROR: config.ini not found!\n";
system("pause");
exit(0);
}
infile >> textRead;
stringLength = strlen(textRead);
pch=strchr(textRead,'"');
while(pch != NULL) {
infile.seekg(pch-textRead-1);
infile >> textRead;
pch = strchr(pch+1,'"');
}
cout << textRead;
infile.close();
Inside your while loop you call:
infile >> textRead;
pch = strchr(pch+1,'"');
When you try to run strchr in the second line, it's still referring back to the previous string you had in textRead NOT the most recently extracted word.
Unfortunately I can't deduce what you're actually trying to do so I can't offer suggestions on how to fix it.
I'm guessing at the contents of config.ini, since you didn't provide it, but it looks like the ifstream is reading just fine. put a cout << textRead << endl; after your infile >> textRead; to check. This is what I'm using for config.ini:
localhost = "foo"
Your logic with seekg and friends seems broken, though. seekg isn't meant to be used to support parsing (in your case, skipping quotes); it's meant to skip over large chunks of file when needed so you don't waste time reading it in. Honestly, I'm not sure what you're doing since pch-textRead-1 could be -1 if the first character is a quote.
Another thing is that infile >> textRead; does not read a line, it reads a word, and discards leading whitespace.
For the record, I omitted
#include <winsock2.h>
#include <mysql/mysql.h>
#include <windows.h>
since it isn't needed.
Related
I'm writing a function that reads line by line from cin and returns when it sees ; character.
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <string.h>
using namespace std;
int read_cmd(char *cmd)
{
cout << "Please enter a string: \n";
cmd[0]='\0';
while(1){
char currentLine[10000];
currentLine[0]='\0';
cin.getline(currentLine,10000);
if (strcmp(currentLine,";")==0){
break;
}
strcat(cmd, "\n");
strcat(cmd, currentLine);
}
return 0;
}
int main(){
char cmd[1000];
while (1){
read_cmd(cmd);
cout<< cmd << endl;
}
}
I then tested it using text fed from another file via pipe.
./read_cmd < test_file
contents of test_file:
line 1
line 2
;
This outputs results just fine, however it gives me a segmentation fault at the end. Is there a way for cin to check if it's coming across an EOF and terminates?
To detect the EOF you should use something like:
while (cin.good() && !cin.eof())
{
// Read the file
}
See the documentation for cin, in particular the good() (for error checking) and eof() member functions.
In particular this example might be helpful.
I would highly suggest the use of the string object for something like this, that way you're not wasting space, as well as ensuring that you have enouch space. You can also do it without a loop.
string currentLine;
getline(cin, currentLine, ';');
Now, if you need to get just the last line with has the semi-colon, a loop is necessary, but still you can do it at little more easily.
string currentLine;
while(getline(cin, currentLine)){
if(currentLine.find(";") != string::npos){
break;
}
}
Use strings to pass things around as well. There's always the .clear() method as well that any string has for easy emptying.
string getline
string Object
Here is what I got so far:
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
int characterList = 0;
char* dynamo = new char[1000];
char* buffer = dynamo;
ifstream input("wordlist.txt");
if (input.is_open())
{
input >> dynamo[characterList];
while (input.eof())
{
characterList++;
input >> dynamo[characterList];
cout << dynamo[characterList];
}
}
else
{
cout << "File not opened" << endl;
}
return;
}
I'm a beginner so I do apologize if this looks like terrible coding practice. I created a text file with a quote from Bill Cosby that I'm trying to read one word at a time. The quote is "I don't know the key to success, but the key to failure is trying to please everybody." I'm trying to read one word at a time from a text document ignoring punctuation. I know there are a lot of questions similar to this, but they are using code that I have not learned so I'm sorry for having a repeating question. I have not learned getline (I used cin.getline) and #include <string>.
Edit: I forgot to mention, so I'm sorry for not doing so earlier, but I'm studying dynamic memory allocation which is why I'm using the new char[1000].
I'd suggest you to use std::string instead of manually allocating buffers on the heap with new[] and trying to read text manually from the file into those buffers (and don't forget to free the buffer with proper delete[] calls!).
C++ input stream classes like std::ifstream can simply read text into std::string instances thanks to a proper overload of operator<<.
The syntax is as simple as:
string word;
while (inFile >> word)
{
cout << word << endl;
}
Here's a complete compilable sample code for you to experiment and learn:
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main()
{
ifstream inFile("test.txt");
if (inFile.is_open())
{
string word;
while (inFile >> word)
{
cout << word << endl;
}
}
else
{
cout << "Can't open file." << endl;
}
}
This is the output I got on a test text file having the content specified in your question:
I
don't
know
the
key
to
success,
but
the
key
to
failure
is
trying
to
please
everybody.
NOTE
Of course, once you have your words read into a std::string instance, you can store them in a container like std::vector<std::string>, using its push_back() method.
I would do something like this:
#include <iostream>
#include <string>
#include <fstream>
int main() {
std::string array[6];
std::ifstream infile("Team.txt");
std::string line;
int i = 0;
while (std::getline(infile, line)) {
array[i++] = line;
}
return 0;
}
based on this answer.
Here, we assume we have to read 6 lines from the file "Team.txt". We use std:::getline() and we put inside a while so that we read all the file.
At every iteration, line holds the current line of the file read. Inside the body we store it in array[i].
#include <iostream>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <string>
#include <iomanip>
#include <fstream>
#include <stdio.h>
using namespace std;
int main()
{
ifstream file;
string filename;
char character;
int letters[153] = {};
cout << "Enter text file name: ";
cin >> filename;
file.open(filename.c_str());
if (! file.is_open())
{
cout << "Error opening file. Check file name. Exiting program." << endl;
exit(0);
}
while (file.peek() != EOF)
{
file >> character;
if(!file.fail())
{
letters[static_cast<int>(character)]++;
}
}
for (int i = 0; i <= 153; i++)
{
if (letters[i] > 0)
{
cout << static_cast<char>(i) << " " << letters[i] << endl;
}
}
exit(0);
}
#endif
Hi everyone, my current code counts the frequency of each letter from a text file. However, it does not count the number of blank spaces. Is there a simple way to printout the number of blank spaces in a .txt file?
Also, how come when I'm trying to access a vector item, I run into a seg fault?
For example, if I use:
cout << " " + letters[i] << endl;, it displays a segfault. Any ideas?
Thank you so much.
By default, iostreams formatted input extraction operations (those using >>) skip past all whitespace characters to get to the first non-whitespace character. Perhaps surprisingly, this includes the extraction operator for char. In order to consider whitespace characters as characters to be processed as usual, you should alter use the noskipws manipulator before processing:
file << std::noskipws;
Don't forget to set it back on later:
file << std::skipws;
What if you're one of those crazy people who wants to make a function that leaves this aspect (or in even all aspects) of the stream state as it was before it exits? Naturally, C++ provides a discouragingly ugly way to achieve this:
std::ios_base::fmtflags old_fmt = file.flags();
file << std::noskipws;
... // Do your thang
file.flags(old_fmt);
I'm only posting this as an alternative way of doing what you're apparently trying. This uses the same lookup table approach you use in your code, but uses an istreambuf_iterator for slurping unformatted (and unfiltered) raw characters out of the stream buffer directly.
#include <iostream>
#include <fstream>
#include <iterator>
#include <climits>
int main(int argc, char *argv[])
{
if (argc < 2)
return EXIT_FAILURE;
std::ifstream inf(argv[1]);
std::istreambuf_iterator<char> it_inf(inf), it_eof;
unsigned int arr[1 << CHAR_BIT] = {};
std::for_each(it_inf, it_eof,
[&arr](char c){ ++arr[static_cast<unsigned int>(c)];});
for (int i=0;i<sizeof(arr)/sizeof(arr[0]);++i)
{
if (std::isprint(i) && arr[i])
std::cout << static_cast<char>(i) << ':' << arr[i] << std::endl;
}
return 0;
}
Executing this on the very source code file itself, (i.e. the code above) generates the following:
:124
#:4
&:3
':2
(:13
):13
*:1
+:4
,:4
/:1
0:3
1:2
2:1
::13
;:10
<:19
=:2
>:7
A:2
B:1
C:1
E:2
F:1
H:1
I:3
L:1
R:2
T:2
U:1
X:1
[:8
]:8
_:10
a:27
b:1
c:19
d:13
e:20
f:15
g:6
h:5
i:42
l:6
m:6
n:22
o:10
p:1
r:37
s:20
t:34
u:10
v:2
z:2
{:4
}:4
Just a different way to do it, but hopefully it is clear that usually the C++ standard library offers up elegant ways to do what you desire if you dig deep enough to find whats in there. Wishing you good luck.
I am working on a small program that takes a input file and processors the data in the file. With my current code (see below) when you enter a valid file name it just freezes the command line (drops down a line and just shows a flashing _ ) and I have to kill the program to get out. If you enter a invalid file name the if(!file) gets called and runs fine.
Whats really odd is that if I put a debugging cout above that if statement it will not get called if the file name is correct. Hope you can help and if you need more info let me know!
This is my current code:
using namespace std;
#include <iostream>
#include <stdexcept>
#include <string>
#include <fstream>
#include <vector>
#include <cctype>
#include "Student.h"
int main(){
string filename, name;
char *inputfile;
ifstream file;
vector<Student> students;
const int SIZE = 200;
char buffer [SIZE];
int regno, i;
cout << "Enter file name: ";
cin >> filename;
inputfile = const_cast<char*> (filename.c_str());
file.open(inputfile);
if (!file){
cout << "Failed to open " << filename << endl;
exit(1);
}
while (!file.eof()){
file.getline(buffer, SIZE);
i = 0;
regno = 0;
while (isdigit(buffer[i])){
regno = (regno*10)+buffer[i];
}
cout << regno;
}
file.close();
}
Your problems is that you never increase i in the cycle.
Here:
i = 0;
regno = 0;
while (isdigit(buffer[i])){
regno = (regno*10)+buffer[i];
}
You go into infinite cycle as i always stays 0.
Also why do you do the const_cast? You can open using a const char * too. So you can write this:
cin >> filename;
file.open(filename.c_str());
And code will still work.
There's another problem in your code concerning the use of getline() and eof(). The idiomatic way to read a file line-by-line is this:
std::string line;
while(getline(in, line)) {
// handle line here
}
in refers to some input stream like a std::ifstream or std::cin. The point is that reading a line can fail (e.g. due to EOF), which you check in above loop. Your version only checks if EOF was encountered before but not that the subsequent getline() call actually yielded any data.
i have a little problem on writing the string into a file,
How can i write the string into the file and able to view it as ascii text?
because i am able to do that when i set the default value for str but not when i enter a str data
Thanks.
#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;
int main()
{
fstream out("G://Test.txt");
if(!out) {
cout << "Cannot open output file.\n";
return 1;
}
char str[200];
cout << "Enter Customers data seperate by tab\n";
cin >> str;
cin.ignore();
out.write(str, strlen(str));
out.seekp(0 ,ios::end);
out.close();
return 0;
}
Please use std::string:
#include <string>
std::string str;
std::getline(cin, str);
cout << str;
I'm not sure what the exact problem in your case was, but >> only reads up to the first separator (which is whitespace); getline will read the entire line.
Just note that >> operator will read 1 word.
std::string word;
std::cin >> word; // reads one space seporated word.
// Ignores any initial space. Then read
// into 'word' all character upto (but not including)
// the first space character (the space is gone.
// Note. Space => White Space (' ', '\t', '\v' etc...)
You're working at the wrong level of abstraction. Also, there is no need to seekp to the end of the file before closing the file.
You want to read a string and write a string. As Pavel Minaev has said, this is directly supported via std::string and std::fstream:
#include <iostream>
#include <fstream>
#include <string>
int main()
{
std::ofstream out("G:\\Test.txt");
if(!out) {
std::cout << "Cannot open output file.\n";
return 1;
}
std::cout << "Enter Customer's data seperated by tab\n";
std::string buffer;
std::getline(std::cin, buffer);
out << buffer;
return 0;
}
If you want to write C, use C. Otherwise, take advantage of the language you're using.
I can't believe no one found the problem. The problem was that you were using strlen on a string that wasn't terminated with a null character. strlen will keep iterating until it finds a zero-byte, and an incorrect string length might be returned (or the program might crash - it's Undefined Behavior, who knows?).
The answer is to zero-initialize your string:
char str[200] = {0};
Supplying your own string as the value of str works because those in-memory strings are null-terminated.