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cpointerscharaddition

Addition of an integer to a string

I have this code in c and it's working properly.

char* str2 = string + (str_len - end_len);

str_len and end_len are two integers and string is another char pointer string.

I don't understand why I am able to add an integer to a character pointer string.

Shouldn't this give a type error?

Solution

  • str2 will be assigned the pointer value of string + (str_len - end_len). If offset = str_len - end_len < 0 or offset > size of string (array) + 1 then it's undefined behavior (note: sizeof "hello " counts the trailing '\0' for a string hence the -1). Here's an example:

    #include <stdio.h>

int main() {
    char string[] = "hello world";
    char *str2 = string + (sizeof "hello " - 1);
    printf("%s\n", str2);
}

    prints:

    world