Issue regarding size_t - c++

Question

If you go in my post history you'll see that i'm trying to develop an interpreter for a language that i'm working on. I want to use size_t using two different codes, but they all return nothing.
Here is the post of what i was trying: http://stackoverflow.com/questions/1215688/read-something-after-a-word-in-c
When i try to use the file that i'm testing it returns me nothing. Here is the sample file(only a print function that i'm trying to develop in my language):
print "This is a print function that i'm trying to develop in my language"
But remember that this is like print in Python, what the user type into the quotes(" ") is what have to be printed to all, remember that the user can choose what put into the quotes, then don't put something like a simple cout, post something that reads what is inside the quotes and print it to all. But here is the two test codes to do this, but all of they don't returns nothing to me:
#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
int main( int argc, char* argv[] )
{
// Error Messages
string extension = argv[ 1 ];
if(argc != 2)
{
cout << "Error syntax is incorrect!\nSyntax: " << argv[ 0 ] << " <file>\n";
return 0;
}
if(extension[extension.length()-3] != '.')
{
cout << "Extension not valid!" << endl;
cout << "Default extension *.tr" << endl;
return 0;
}
if(extension[extension.length()-2] != 't')
{
cout << "Extension not valid!" << endl;
cout << "Default extension *.tr" << endl;
return 0;
}
if(extension[extension.length()-1] != 'r')
{
cout << "Extension not valid!" << endl;
cout << "Default extension *.tr" << endl;
return 0;
}
// End of the error messages
ifstream file(argv[ 1 ]);
if (!file.good()) {
cout << "File " << argv[1] << " does not exist.\n";
return 0;
}
string linha;
while (!file.eof())
{
getline(file, linha);
if (linha == "print")
{
size_t idx = linha.find("\""); //find the first quote on the line
while ( idx != string::npos ) {
size_t idx_end = linha.find("\"",idx+1); //end of quote
string quotes;
quotes.assign(linha,idx,idx_end-idx+1);
// do not print the start and end " strings
cout << "quotes:" << quotes.substr(1,quotes.length()-2) << endl;
//check for another quote on the same line
idx = linha.find("\"",idx_end+1);
}
}
}
return 0;
}
The second:
#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
int main( int argc, char* argv[] )
{
// Error Messages
string extension = argv[ 1 ];
if(argc != 2)
{
cout << "Error syntax is incorrect!\nSyntax: " << argv[ 0 ] << " <file>\n";
return 0;
}
if(extension[extension.length()-3] != '.')
{
cout << "Extension not valid!" << endl;
cout << "Default extension *.tr" << endl;
return 0;
}
if(extension[extension.length()-2] != 't')
{
cout << "Extension not valid!" << endl;
cout << "Default extension *.tr" << endl;
return 0;
}
if(extension[extension.length()-1] != 'r')
{
cout << "Extension not valid!" << endl;
cout << "Default extension *.tr" << endl;
return 0;
}
// End of the error messages
ifstream file(argv[ 1 ]);
if (!file.good()) {
cout << "File " << argv[1] << " does not exist.\n";
return 0;
}
string linha;
while (!file.eof())
{
getline(file, linha);
if (linha == "print")
{
string code = " print \" hi \" ";
size_t beg = code.find("\"");
size_t end = code.find("\"", beg+1);
// end-beg-1 = the length of the string between ""
cout << code.substr(beg+1, end-beg-1);
}
}
return 0;
}
And here is what is printed in the console:
ubuntu#ubuntu-laptop:~/Desktop/Tree$ ./tree test.tr
ubuntu#ubuntu-laptop:~/Desktop/Tree$
Like i said, it prints me nothing.
See my post in D.I.C.: http://www.dreamincode.net/forums/showtopic118026.htm
Thanks,
Nathan Paulino Campos

Answer 1

Your problem is the line
if (linha == "print")
which assumes the entire line just read in is "print", not that the line STARTS with print.
Also, why would you use 3 separate checks for a .tr extension, vs. just checking the end of the filename for ".tr"? (You should also be checking that argv[1] is long enough before checking substrings...)

Answer 2

getline(file, linha) will read an entire line from the file, so linha never be equal to print.