C语言：模拟实现printf函数——my_printf函数哦

#define _CRT_SECURE_NO_WARNINGS 10
#include<stdio.h>
#include<stdarg.h>
#include<stdlib.h>
#include<assert.h>
#include<string.h>

//int printf( const char *format [, argument]... );
//模拟实现printf函数，可以实现my_printf（“s ccc”，“hello”，‘b’，‘i’，‘t’）

char *int_str(int nums)
{
char str[32] = "0";
int i = 0;
for (i = 31; i >= 0; i--)
{
str[i] = (nums & 1) + '0';
nums >>= 1;
}
printf("%s\n", str);
}

int my_printf(const char *format, ...)
{
assert(format);
va_list arg_list;
va_start(arg_list, format);
int count = 0;
const char *start = format;
while (*start != '\0')
{
if (*start == '%')
{
start++;
switch (*start)
{
case 's':
{
char *ret = va_arg(arg_list, char *);
fputs(ret, stdout);
count = count + strlen(ret);
}
break;
case 'c':
{
char _c = va_arg(arg_list, char);
putchar(_c);
count++;
}
break;
case 'd':
{
int _d = va_arg(arg_list, int);
char buf[10];
_itoa(_d, buf,10);
fputs(buf, stdout);
count = count + strlen(buf);
}
break;

case 'v':
{
int _dd = va_arg(arg_list, int);
char *array = int_str(_dd);
fputs(array, stdout);
count = count + strlen(array);
}
break;
}
start++;
continue;
}
putchar(*start);
start++;
count++;
}
va_end(arg_list);
return count;
}

int main()
{
my_printf("%s %c%c%c", "hello", 'b', 'i', 't');
system("pause");
return 0;
}