CODEWITHSUNDEEP
carrays
Harris.C
Harris.C

Reputation: 33

How to modify the content in one single string in C?

It's simple question but i just couldn't figure out. I've been trying to make an approach to replace the content of one string by part of it's content like, replace "He is a boy" to "is a boy" as follow:

int main() {
    char array[] = "he is a boy";
    strcpy(array, &array[3]);
    printf("%s\n", array);
}

But the program just stopped at strcpy statement. Is there any problem using strcpy or any other method to achieve the same purpose?? BTW, I'm using X-code on my mac. Thx~

Upvotes: 0

Views: 64

Answers (1)

unwind
unwind

Reputation: 399803

Yes, you cannot use strcpy() when the source and destination overlap. This is clearly stated in the manual page:

The strings may not overlap, and the destination string dest must be large enough to receive the copy.

You can use memmove(), but then you have to specify the length and probably deal with termination issues yourself since it's a general-purpose memory-manipulation function, and not designed for strings specifically.

In your case since you're copying the tail, we can just include the termination and be fine:

int main(void) {
    char array[] = "he is a boy";
    memmove(array, array + 3, 9);
    printf("%s\n", array);
    return 0;
}

Upvotes: 3

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