C++ arguments comparison

Question

Hello I am trying to read some arguments and process them but when i try to read arguments via if else ladder a problem occurs

int main (int argc, char *argv[])
{
cout << argv[1] << endl;
if (argv[1] == "process")
    cout << "yes" << endl;
else
    cout << "no" << endl;
}

This code outputs:

process

no

Do you know why the output is no instead of yes ?

By the way I tried to convert either one of them to a string and compared it with another surprisingly it worked, even though I couldn't figure out why.

Answer 1

argv[1] is a pointer, actually a char * (see the definition char *argv[] ), and in your code "process" (which is a const char [] ) also decays to a const char * , so you are basically comparing two char * .

Since char * are simply pointers, then you are comparing addresses, not "string", and obviously argv[1] and "process" are not stored at the same address.

If you convert one of the two to std::string , then you are comparing a std::string and char * (or const char * ), and std::string has an overloaded operator== for char * so it works.

You could compare "C strings" (aka char arrays) using strcmp or strncmp .

Answer 2

argv[1] == "process" compares pointers. Use strcmp to compare the strings behind the pointers:

#include <string.h>

int main (int argc, char *argv[])
{
cout << argv[1] << endl;
if (strcmp(argv[1],"process")==0)
    cout << "yes" << endl;
else
    cout << "no" << endl;
}