Assign values to variables in c file by reading excel sheet - c++

Question

I need to assign values to variables in C file by reading an excel sheet. I have written a code but only the last variable has been assigned a value since I have used for loop.It is overwriting the values assigned to the previous variables as I am creating a different output file after assigning values.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
string s1, s2, s3,s4;
string filename, text, line;
string cfilename,funcname, signal, value;
int i , k , m;
cout << "Enter excel filename" << endl;
cin >> filename;
cout << "How many lines of text are in the file?" << endl;
cin >> m;
fstream file(filename);
if (!file) {
cerr << "No such file exists." << endl;
exit(1);
}
if (file.is_open()) {
while (file.eof()==0){
for (k = 0; k < m; k++) { //Loops for as many lines as there are in the file
for (i = 0; i < 4; i++) { //Loops for each comma-separated word in the line
if (i == 0){
getline(file, text, ',');
cfilename=text;
cout << cfilename << '\t';}
else if (i == 1){
getline(file, text, ',');
funcname=text;
cout << funcname << '\t';}
else if (i == 2){
getline(file, text, ',');
signal=text;
cout << signal << '\t';}
else if (i == 3){
getline(file, text, '\n');
value=text;
cout << value << '\n';}
}
string s1=signal,s2=value;
s2 = s2 + "; //";
int offset, inset;
string line;
string search=s1;
fstream cfile(cfilename);
fstream fileOutput;
fileOutput.open("output.c");
if(cfile.is_open() && fileOutput.is_open()) {
while(!cfile.eof()) {
getline(cfile, line);
if ((offset = line.find(funcname)) != string::npos){
cout << "found: " << funcname << endl;
string line1;
fileOutput << line << '\n';
skip:
while(getline(cfile,line1)){
if((inset=line1.find(search, 0)) !=string::npos){
cout<<"found: " << search << endl;
string s3 = s1+ "=" +s2;
//cout<<s3;
line1.replace( inset, inset+s1.size(), s3 );}
fileOutput << line1 << '\n';
goto skip;
}
getchar(); }
fileOutput << line << '\n'; }
cfile.close();
fileOutput.close();
}
}
}
}
file.close();
getchar();
return 0;
}
I am trying to search a function first and then variables inside that function.
Need some help here.

Answer 1

I'm not sure it's this the problem but... I thing the while () is too much.
when you have readed the m lines of the file, your
while (file.eof()==0)
result true because you haven't read nothing past the end of file.
So you read other m lines (failing but without controls about the success of the reading).
EDIT: I think you should write something like
cout << "Enter excel filename" << endl;
cin >> filename;
fstream file(filename);
if (!file) {
cerr << "No such file exists." << endl;
exit(1);
}
while ( getline(file, cfilename, ',') && getline(file, funcname, ',')
&& getline(file, signal, ',') && getline(file, value, '\n')) {
cout << cfilename << '\t' << funcname << '\t' << signal << '\t'
<< value << '\n';
string s1=signal,s2=value;
[...]

Answer 2

The program does exactly what you asked it to do:
you read a CSV file (excel format is binary!) line by line
for each line in csv:
you erase the output file because you open a fstream without specifying ios::ate
search something in a source file and write to the output file.
As you erase the output file at every new line from the input CSV file, you cannot get more than the last operation.
It would be much simpler if you opened the output file once outside of the loop.
And... while (file.eof() == 0) is an anti-pattern. You look whether you have reached end of file before trying to read a line, and then read 4 values when the first getline have set the eof flag. You must test for eof immediately after a read and not before...