Implement strcmp function in C

Question

I want to Implement strcmp so this is what i have try:

int compare(char *str1, char *str2, int maximumCharactersToCompare)
{
    int i;
    int result = 0;
    for (i = 0; i < maximumCharactersToCompare; i++)
    {
        if (str1[i] > str2[i])
            result = 1;
        else if (str1[i] < str2[i])
            result = -1;
        if (str1[i] == '\0' || str1[i] == '\0')
            break;
    }

    return result;
}

My usage:

char str1[127];
char str2[127];

printf("Please enter first string: ");
scanf("%s", str1);

printf("Please enter second string: ");
scanf("%s", str2);

int result = compare(str1, str2, 127);

So my problem is that if i try to compare "test" and "test " this return 0 and i can see that str2 is equat to "test" instead of "test " and thats why my result is 0

test lengths first. If they don't match, then return "not equal". Once you have equal lengths, then you can safely compare. — Jean-François Fabre, Nov 05 '17 at 18:15
But why my both str1 and str2 get the value "test" although i typed str2="test " — user979033, Nov 05 '17 at 18:20
@Jean-FrançoisFabre there is no reason to test any lengths. The terminating `\0` of the shorter string will be *inequal* to the character in the longer string. — Antti Haapala -- Слава Україні, Nov 05 '17 at 18:52
@AnttiHaapala that's true. Why recoding strcmp? (well I recoded it in assembly, but I didn't have access to any C library) — Jean-François Fabre, Nov 05 '17 at 19:56

score 0 · Answer 1 · answered Nov 05 '17 at 18:21

0

you type

if (str1[i] == '\0' || str1[i] == '\0')

try

if (str1[i] == '\0' || str2[i] == '\0')

answered Nov 05 '17 at 18:21

Cesar Augusto

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Implement strcmp function in C

1 Answers1