print.c

linux下的printf函数实现

#include <stdio.h>
#include <stdlib.h>
#include "mystring.h"

int _printf(const char *fmt, ...)
{
	int *stack = (int *)&fmt;
	char *str;

	str = (char *)malloc(sizeof(char) * MAX_LEN);
	if(!str)
		return -1;
	char *buf = (char *)malloc(sizeof(char) * MAX_LEN);
	if(!buf)
		return -1;

	char *pcur = buf;
	
	while(*fmt)
	{
		if(*fmt == '%')
		{
			switch(*(fmt + 1))
			{
				case '%':
					*pcur++ = '%';
					fmt += 2;
					break;
				case 'c':
					*pcur++ = *(++stack);
					fmt += 2;
					break;
				case 'd':
					str = int_char(*(++stack));
					while(*str)
						*pcur++ = *str++;
					fmt += 2;
					break;
				case 's':
					istrcpy(str, (char *)*(++stack));
					while(*str)
						*pcur++ = *str++;
					fmt += 2;
					break;
				case 'p':
					str = uint_hex(*(++stack));
					fmt += 2;
					*pcur++ = '0';
					*pcur++ = 'x';
					while(*str)
						*pcur++ = *str++;
					break;
				default:
					*pcur++ = *fmt++;
			}
		}
		else
			*pcur++ = *fmt++;
	}

	*pcur = '\0';

	while(*buf)
		putchar(*buf++);

	return 1;
}

int main()
{
	int i;
	char *str = "STRING";
	char *str2 = "new printf";
	int a[10000] = {1, 2, 3};
	_printf("_printf:\n");
	_printf("%dHel%slo%c, i%%Linux%d, %c, %s, %p\n", 7555555, str2, 'h', 0, 'A', str, &str);
	_printf("printf:\n");
	printf("%dHel%slo%c, i%%Linux%d, %c, %s, %p\n", 7555555, str2, 'h', 0, 'A', str, &str);

	for(i = 0; i < 3; i++)
	{
		printf("a[%d] = %d\n", i, a[i]);
		_printf("a[%d] = %d\n", i, a[i]);
	}
	return 0;
}