《C面试真题精讲》程序摘录

#include <stdio.h>

#include <stdlib.h>

//#include <assert.h>

#if 0

char

*mystrcpy(char *dest,char *src)

{
//char *p = dest;
char *p;
p = dest;

while (*src != '\0')
{
*dest++ = *src++;
printf("%s\n",dest);
//printf("%s\n",p);
//我自己添加的
//printf("%s\n",src);
//我自己添加的
}

return p;

}

#endif

char *mystrcpy(char *dest,char *src)

{
char *d = dest;
// 输入参数的备份
char *s = src;
int count = 0;

//assert(dest);
//assert(src);

if (src == dest)
{
return src;
}
count = strlen(src) + 1;
if (count <= 1)
{
return 0;
}

if (dest < src || dest >= (src + count))
{
while (count--)
{
*d++ = *s++;
}
} else 
{
d = dest + count;
s = src + count;
while (count--)
{
*d-- = *s--;
}
}

return dest;

}

int 

main(void)

{
char *dest,*src,*p;
src = "Hello world!";

p = mystrcpy(dest,src);

printf("%s\n",dest);
printf("%s\n",p);
printf("%s\n",src);

return 0;

}