sprintf 加入了%号的功能，看起来能够正常显示字符了，是不是觉得更耐看了。

本文链接：https://blog.youkuaiyun.com/weixin_39410618/article/details/82819728

本文详细介绍了如何在C语言中自定义一个类似printf的函数，包括格式化字符串处理、变量参数列表管理和数值转换等核心功能。通过源代码解析，读者可以深入理解C语言的变长参数和类型转换机制。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

百度网盘下载地址：

https://pan.baidu.com/s/1_-IznMWL3z1CROziiD6mCw

#include <stdio.h>
typedef char *va_list;



#define __va_rounded_size(TYPE) \
(((sizeof(TYPE)+sizeof(int)-1)/sizeof(int))*sizeof(int))
#define va_start(AP, LASTARG) \
(AP=((char *)&(LASTARG)+__va_rounded_size(LASTARG)))


#define va_end(AP) ((va_list)0)

#define va_arg(AP, TYPE) \
(AP+=__va_rounded_size(TYPE), \
*((TYPE *)(AP-__va_rounded_size(TYPE))))




int myprintf(char *buf, char *fmt, ...);

void itoa(int num, char *buf, unsigned int base);

unsigned int div(unsigned int *n, unsigned int b);

int main(void) {

	char buf[0x100];

	myprintf(buf, "   %s %% %%%    %d    %x     %c  \
	%s", "Hello World!", 0xfffe, 65535, 'c', "sssss");

	printf("%s", buf);

}



int myprintf(char *buf, char *fmt, ...) {

	va_list ap;

	va_start(ap, fmt);

	char buf1[64], *temp1;

	int d;

	char *s, c;
	while (*fmt) {
		if (*fmt == '%') {
			++fmt;
	switch (*fmt) {
		case '%':
			*buf++ = '%';
			fmt++;
			break;
		case 's':
			s = (char *)va_arg(ap, char *);
//    printf("%s\n", s);
    while(*s)

     *buf++ = *s++;
			fmt++;
    break;

   case 'c':
    c = (char)va_arg(ap, char);

//    printf("%c\n", c);

     *buf++ = c;
			fmt++;
    break;

   case 'd':

    d = (int)va_arg(ap, int);

//    printf("%d\n", d);

    itoa(d, buf1, 10);

    temp1 = buf1;

    while (*temp1) {

    *buf++ = *temp1++;

    }

//    printf("*************%s\n", buf1);
			fmt++;
    break;

   case 'x':

    d = (int)va_arg(ap, int);

//    printf("%d\n", d);

    *buf++ = '0';
    *buf++ = 'x';

    itoa(d, buf1, 16);

    temp1 = buf1;

    while (*temp1) {

    *buf++ = *temp1++;

    }

//    printf("*************%s\n", buf1);

			fmt++;
    break;

 //  case ' ':

//    printf("|Space|\n");

 //   *buf++ = ' ';

 //   break;

				}
			} else {
		*buf++ = *fmt++;
		continue;
		}
	} 

 va_end(ap);
 *buf = '\0';

}



unsigned int div(unsigned int *n, unsigned int b) {

 int res;

 res = *n % b;

 *n = *n / b;

 return res;

}



void itoa(int num, char *buf, unsigned int base) {

 char digits[16] = "0123456789abcdef";

 char temp[64];

 int i = 0;

 while (num)

  *(temp + i++) = digits[div(&num, base)];

 while (i-- > 0)

  *buf++ = *(temp + i);

 *(buf) = '\0';

}