strings.c

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/**
 * strings.c
 *
 * Playing with C strings.
 */
#include <string.h>
#include <stdio.h>

/**
 * Here we pass in a string to a function. In this case, 'str' decays to a
 * pointer and now we can't determine how big the array is.
 */
void my_func(char *str) {
    printf("String length is: %lu\n", strlen(str));
    /* Inside the function, str is now just a pointer (decayed) */
    printf("String sizeof is: %lu\n", sizeof(str));
}

int main(void) {

    char str1[] = "Hello world";
    char str2[] = "Goodbye world";

    printf("%s\n", str1);
    printf("%s\n", str2);

    /* Insert a NUL byte into the middle of the string */
    str1[5] = '\0';

    printf("%s\n", str1);

    /* Print out a substring, starting from 7th character */
    printf("%s\n", &str1[6]);

    printf("String length is: %lu\n", strlen(str2));
    /* Down here, C knows that this is an array: */
    printf("String sizeof is: %lu\n", sizeof(str2));

    my_func(str2);

    /* Just for fun... how big are these data types? */
    printf("sizeof(char) : %lu\n", sizeof(char));
    printf("sizeof(int) : %lu\n", sizeof(int));
    printf("sizeof(long) : %lu\n", sizeof(long));
    printf("sizeof(int *) : %lu\n", sizeof(int*));
    return 0;
}