As soon as I add the below code this programs ends showing this error message:
Process returned -1073741819 (0xC0000005)
If I run those code separately then both of them work.
I used sstream and array too but combined they do not work properly.
#include <sstream>
#include <string>
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
string input = "touch world.txt this.txt is.txt sentence.txt";
string word;
int length = 0;
for(int a = 0;a<input.length();a++){
if(input[a] == ' '){
length++;
}
}
string filesNameArr[length];
int number = 0;
// hello world this is sentence
for(auto x:input)
{
if(x==' ')
{
filesNameArr[number] = word;
word.erase();
number++;
}
else
word=word+x;
}
filesNameArr[number] = word;
number = 0;
//when i add the below code it generates error and stops
ofstream outFile[41];
stringstream sstm;
for (int i=0;i<41 ;i++)
{
sstm.str("");
sstm << "subnode" << i;
outFile[i].open(sstm.str().c_str());
}
return 0;
}
length is one less than the number of words in your string as you are only counting the number of spaces. This means your final filesNameArr[number] = word causes undefined behaviour and will probably corrupt the stack.
string filesNameArr[length]; uses a variable length array which is not valid c++. If you use a std::vector instead you can skip the initial counting of the words completely:
std::vector<std::string> filesNameArr;
for(auto x:input)
{
if(x==' ')
{
filesNameArr.push_back(word);
word.erase();
}
else
{
word+=x;
}
}
filesNameArr.push_back(word);
You can use std::stringstreams built in ability to read words from strings to make this even simpler:
std::stringstream sinput(input);
std::vector<std::string> filesNameArr;
std::string word;
while (sinput >> word)
{
filesNameArr.push_back(word);
}
so, I`m new to c++. My task is parse text file that look like:
RE002%%
RE002%%
RE002%%
RE002%%
RE002%%
RE004%on%
$GPGGA,124749.80,5543.3227107,N,03739.1366738,E,1,08,1.11,147.9635,M,14.4298,M,,*5C
$GPGSV,3,1,10,27,13,078,43,05,31,307,48,16,24,042,43,02,10,267,43*7D
$GPGSV,3,2,10,26,03,031,36,07,75,215,51,09,57,121,53,30,40,234,50*76
$GPGSV,3,3,10,23,29,117,46,04,36,114,46*70
$GPGGA,124749.90,5543.3227105,N,03739.1366737,E,1,08,1.11,147.9664,M,14.4298,M,,*54
RE005%off%
And it continuous for few thousand lines.I need to find where it writes RE004%on% and start processing lines in this loop until it finds RE005%off% and do it over and over until it file ends. I was trying to do it with line.find, but I am pretty sure it is wrong way to solve this problem
#include <iostream>
#include <fstream>
#include <string>
#include <stdlib.h>
using namespace std;
int main() {
string line, dollar, star, Checksum;
float *t0 = NULL;
int tount = 0;
int k;
ifstream logs_("C:/Users/Olya/Desktop/LogGLO.txt");
ofstream tout("outLOGTime.txt");
ofstream pout("outLOGPot.txt");
if (logs_.is_open())
{
while(getline(logs_,line))
{
line.find("RE004%on%")
k = 0;
if
dollar = line.find_first_of('$');
star = line.find_first_of('*');
Checksum = line.substr(line, dollar, star - dollar);
for (size_t i = 0; i < Checksum.size(); i++)
{
}
if (line.substr(0,6) == "$GPGSV")
{
for (size_t i = 0, N = 7; i < line.size(); i++)
{
if (line[i] == ',') k++;
if(k == N)
{
pout << line.substr(i+1,2) << endl;
if ((N += 4) > 19) break;
}
}
}
logs_.close();
}
}
else
cout<<"File is not open"<<'\n';
tout.close();
pout.close();
return 0;
}
Unfortunately your description si very unclear. Also by reading your code, I can really not understand, what you intent to do. And you edited your text and changed description. Not so easy for me
But, I made an educated guess. . .
I read all data between your given delimiters, validate the checksum and split the lines into tokens. Finally I store all the lines-with-Tokens in a vector. Then I filter for a specific value and output a column.
Please stude and try to understand. It is not so complicated.
Thank you
#include <iostream>
#include <regex>
#include <vector>
#include <iterator>
#include <string>
#include <utility>
#include <algorithm>
#include <functional>
#include <numeric>
#include <fstream>
const std::regex re{ R"(\$(.*)\*[abcdefABCDEF\d]{2})" };
const std::regex delimiter{ "," };
using Tokens = std::vector<std::string>;
std::tuple<bool, Tokens> checkString(const std::string& str) {
// Return value of the function. Assume that string is not ok
std::tuple<bool, std::vector<std::string>> result(false, {});
// We want to find a string in the given format
std::smatch sm{};
if (std::regex_match(str, sm, re)) {
// OK, found. Validate checksum
if (std::string s = sm[1];std::stoul(str.substr(str.size() - 2), nullptr, 16) == std::accumulate(s.begin(), s.end(), 0U, std::bit_xor<unsigned char>())) {
// Tokenize string
Tokens tokens(std::sregex_token_iterator(str.begin(), str.end(), delimiter, -1), {});
// Build return value
result = std::make_tuple(true, std::move(tokens));
}
}
return result;
}
int main() {
std::vector<Tokens> csvData{};
// Open file and check if it is open
if (std::ifstream logs("r:\\LogGLO.txt"); logs) {
// Shall we process text lines or not
bool processingActive{ false };
// Read all lines of files
for (std::string line{}; std::getline(logs, line);) {
// Check, if we should start or stio processing of the lines
if (line.substr(0, 9) == std::string("RE004%on%")) processingActive = true;
if (line.substr(0, 10) == std::string("RE005%off%")) processingActive = false;
// Check and read csv data
if (processingActive) {
const auto [ok, data] = checkString(line);
if (ok) csvData.push_back(std::move(data));
}
}
}
// So, now we have read all csv data
// Show eight column of GPGSV data
for (const Tokens& t : csvData)
if (t[0] == "$GPGSV")
std::cout << t[7] << "\n";
return 0;
}
I need a program to take a string and replace spaces with increasing numbers.
#include <cstring>
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
// Get the String
string str = "this essay needs each word to be numbered";
int num = 1;
string x = num;
int i = 0;
// read string character by character.
for (i < str.length(); ++i) {
// Changing the loaded character
// to a number if it's a space.
if (str[i] == ' ') {
str[i] = x;
++num
}
}
// testing outputs
cout << str << endl;
cout << num << endl;
ofstream file;
file.open ("numbered.txt");
file << str;
file.close();
return 0;
}
I had it at the point where it could replace spaces with a letter or symbol and save to a new file but when I tried to make it a number it stopped working. I would need it to say "this1essay2needs3each4word5to6be7numbered
For ease and clarity, change your approach.
Put the string into an istringstream
Extract each space-separated substring and place into an std::vector<string>
Feed the contents of the vector into a stringstream and
use std::to_string(num) to add the numbers between the substrings
e.g.:
std::string str = "this essay needs each word to be numbered";
int num = 1;
std::istringstream istr(str);
std::string temp;
std::vector<std::string> substrs;
while (istr >> temp)
{
substrs.push_back(temp);
}
std::stringstream ostr;
for (auto&& substr : substrs)
{
ostr << substr << std::to_string(num++);
}
Let's break the problem down into parts. We can make a SpaceReplacer object that does the replacement. It has an Output, which it can use as a function to output characters:
template<class Output>
struct SpaceReplacer {
Output output;
int num_spaces;
void input(char c) {
if(c == ' ') {
auto num_as_string = std::to_string(num_spaces);
num_spaces += 1;
for(char digit : num_as_string) {
output(digit);
}
}
else {
output(c);
}
}
};
Every time you input a character, it either outputs the character you input, or it outputs the digits of the number (if the character was a space).
We should write a helper function to make SpaceReplacers:
template<class Output>
SpaceReplacer<Output> makeReplacer(Output output_func) {
return SpaceReplacer<Output>{output_func, 0};
}
Reading one string, returning new string
It's now easy to write a function that replaces spaces in a string.
std::string replaceSpaces(std::string const& input) {
std::string output_string;
// We output chars by appending them to the output string
auto output_func = [&](char c) { output_string += c; };
auto replacer = makeReplacer(output_func);
for(char c : input) {
replacer.input(c);
}
return output_string;
}
Reading input from file, replacing spaces and returning a string
Because we wrote a really generic SpaceReplacer class, we can modify the function so that it'll read input directly from a FILE*
std::string replaceSpaces(FILE* file) {
std::string output_string;
auto output_func = [&](char c) { output_string += c; };
auto replacer = makeReplacer(output_func);
while(true) {
int input_char = fgetc(file);
if(input_char == EOF) {
break;
}
replacer.input(input_char);
}
return output_string;
}
Reading input from one file, immediately appending it to different file with spaces replaced
We can also read directly from one file, and output directly to another file, with no delay. This might be useful if you were processing a very large amount of data.
void replaceSpaces(FILE* input_file, FILE* output_file) {
auto output_func = [=](char c) { fputc(c, output_file); };
auto replacer = makeReplacer(output_func);
while(true) {
int input_char = fgetc(input_file);
if(input_char == EOF) {
break;
}
replacer.input(input_char);
}
}
In this case, you need to use another string for the result.
#include <cstring>
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
// Get the String
string result, str = "this essay needs each word to be numbered qwe qwe wqe qwe qwe qwe q";
int num = 0;
int i;
// read string character by character.
for (i=0; i < str.length(); i++) {
// Changing the loaded character
// to a number if it's a space.
if (str[i] == ' ')
result+=std::to_string(++num);
else
result+=str[i];
}
// testing outputs
cout<<result<<endl;
cout<<num;
ofstream file;
file.open ("numbered.txt");
file << result;
file.close();
return 0;
}
You have to replace it with a character, not by a number.
str[i] = num+'0';
I am reading a file using fstream and getline functions. I want to give a starting position e.g. my file has 13 lines I want to start reading it from 7th line for example. Here is my code:
#include<iostream>
#include <stdlib.h>
#include <string>
#include <vector>
#include<iterator> // for iterators
#include<map>
using namespace std;
int main()
{
string line;
int start= 7;
unsigned long int index;
For( int z=1; z<=13; z++){
if (f_node.is_open())
{
getline(f_node, line);
if ((line.find("$EndNodes") != string::npos))
{
cout << "$EndNodes found file closed .... " << endl;
f_node.close();
return false;
}
// Point index.
int i = 0;
int j = line.find_first_of(" ", i);
index = strtoul((line.substr(i, j)).c_str(), NULL, 0);//
}
}
I am reading only indexes and I want to start it from 7th index How to do it?
To discard some number of lines, something like:
#include <fstream>
#include <string>
int main() {
std::ifstream infile{"myfile.txt"};
std::string line;
int starting_line = 7;
// Read and discard beginning lines
for (int n = 1; n < starting_line; n += 1) {
if (!std::getline(infile, line)) {
// Error or premature end of file! Handle appropriately.
}
}
while (std::getline(infile, line)) {
// Do something with the lines you care about.
}
return 0;
}
Except with actual error checking and handling and such.
"there is no way to tell code the starting position like seekg and tellg?" No. NL is just like any other character, it does not receive any special treatment.
You simply must scan the stream, counting the new-line character:
std::istream& seek_line(std::istream& is, const int n, std::ios_base::seekdir way = std::ios_base::beg)
{
is.seekg(0, way);
int i = 0;
char c;
while (is.get(c) && i < n)
if (c == '\n')
++i;
is.putback(c);
return is;
}
And this is how you use the above function:
int main()
{
using namespace std;
ifstream is{ "c:\\temp\\test.txt" };
if (!is)
return -1;
if (!seek_line(is, 3))
return -2;
string s;
getline(is, s);
cout << s << endl;
return 0;
}
#include <iostream>
#include <string>
#include <vector>
/*
Using STL's string class because the problem does not refer any
limits regarding the number of characters per line.
*/
using namespace std;
int main()
{
string line;
vector<string> lines;
while (getline(cin, line))
{
lines.push_back(line);
}
unsigned int i, u;
unsigned int opening = 1; // 2 if last was opening, 1 if it was closing
for (i = 0; i < (int) lines.size(); i++)
{
for (u = 0; u < (int) lines[u].length(); u++)
{
}
}
return 0;
}
I have that simple code that just reads over a few lines (input file):
"To be or not to be," quoth the Bard, "that
is the question".
The programming contestant replied: "I must disagree.
To `C' or not to `C', that is The Question!"
However, I found that it is SEGFAULTing as it reads a ' ' (space) character on the first line (4th character):
(gdb) run < texquotes_input.txt
Starting program: /home/david/src/oni/texquotes < texquotes_input.txt
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7b92533 in std::string::length() const () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
I really can't understand why, I'm not doing anything inside the loop, I'm just looping.
I already found the problem. It's the inner loop:
for (u = 0; u < (int) lines[u].length(); u++)
{
}
Should be:
for (u = 0; u < (int) lines[i].length(); u++)
{
}
In another answer the index typo was already spotted.
I'd like to add that using range-based for loops those kinds of problems are more difficult to happen, since the loop is kind of more "implicit":
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main()
{
string line;
vector<string> lines;
while (getline(cin, line))
{
lines.push_back(line);
}
for ( const auto& currLine : lines )
{
for ( auto ch : currLine )
{
cout << ch;
}
cout << '\n';
}
}