指定した文字数だけ、文字列をコピー

C

明解Ｃ言語 入門編 > 11. 文字列とポインタ >

指定した文字数だけ、文字列をコピー

C



#include <stdio.h>

#include <string.h>
char* str_ncpy(char* d, const char* s, size_t n)

{

    char* t = d;
    int j = 1;

    unsigned i;

    for (i = 0; i < n; i++)

    {

        if ((*s) && j)

            *d++ = *s++;

        else

        {

            j = 0;

            *d++ = '\0'; /* \0 で 埋める */

        }

    }
    return t;

}
int main(int argc, char* argv[])

{

    int i;

    char* st1 = "1234567890";

    char* st2 = "ABCDE";
    printf("st1 = %s\n", st1);

    printf("st2 = %s\n", st2);

    puts("");
    str_ncpy(st1, st2, 4);

    printf("st1 = %s\n", st1);

    printf("st2 = %s\n", st2);

    puts("");
    str_ncpy(st1, st2, 6);

    printf("st1 = ");

    for (i = 0; i < 10; i++)

        if (st1[i] == '\0')

            putchar(' ');

        else

            putchar(st1[i]);

    putchar('\n');

    printf("st2 = %s\n", st2);

    puts("");
    st1 = "1234567890";

    strncpy(st1, st2, 4);

    printf("st1 = %s\n", st1);

    printf("st2 = %s\n", st2);

    puts("");
    strncpy(st1, st2, 6);

    printf("st1 = ");

    for (i = 0; i < 10; i++)

        if (st1[i] == '\0')

            putchar(' ');

        else

            putchar(st1[i]);

    putchar('\n');

    printf("st2 = %s\n", st2);

    puts("");
    return 0;

}
実行結果


T:\>lesson086\project1.exe

st1 = 1234567890

st2 = ABCDE
st1 = ABCD567890

st2 = ABCDE
st1 = ABCDE 7890

st2 = ABCDE
st1 = ABCD567890

st2 = ABCDE
st1 = ABCDE 7890

st2 = ABCDE