C String Comparison Failure? [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

C String — Using Equality Operator == for comparing two strings for equality

I have the following code;

#include <stdio.h>
#define MAXLINE 2600
char words[4][MAXLINE];
i开发者_如何学运维nt i;

int main(){

    printf("Enter menu option: ");

    scanf("%s", words[i]);

    printf ("\n %s was entered!", words[i]);

    if (words[i]=="help"){
        printf("\nHelp was requested");
    } 
    else 
    { 
        printf("\nCommand not recognized!"); 
    }

}

The array evaluation in the if statement isn't working. I am obviously doing something wrong. Can someone explain to me what?

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You are comparing words[i] and "help" for pointer equality, not string equality. I think you meant: if (strcmp(words[i], "help") == 0) {

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In C, strings (sequences of characters) are treated as arrays of characters. As a result, you shouldn't compare arrays using the == operator.

The array braces [] are just syntactic sugar to hide the pointer arithmetic that's going on under the hood. In general, arr[i] is identical to *(arr + i). Using this information, let's take a look at your comparison:

words[i] -> *(words + i), which is a pointer to an array of characters.

If you want to compare strings, use strncmp.