C语言自定义输入输出函数

//put_put.c -- user-defined output functions
#include <stdio.h>
void put1(const char *);
int put2(const char *);

int main(void)
{
    put1("If I'd as much money");
    put1(" as I could spend,\n");
    printf("I count %d characters.\n",
           put2("I never would cry old chairs to mend."));

    return 0;
}

void put1(const char * string)
{
    while (*string)  /* same as *string != '\0' */
        putchar(*string++);
}

int put2(const char * string)
{
    int count = 0;
    while (*string)
    {
        putchar(*string++);
        count++;
    }
    putchar('\n');

    return(count);
}