007-字符串的三种典型模型
本帖最后由 moc 于 2018-8-8 16:47 编辑1、字符串的拷贝--推演
#include "stdlib.h"
#include "stdio.h"
#include "string.h"
void copy_str2(char *from, char *to)
{
for (;*from != '\0';to++,from++)
{
*to = *from;
}
*to = '\0';
}
// 后缀++的优先级高于*p，所以先执行*p,在执行++，{后缀（先执行在++）}
void copy_str3(char *from, char *to)
{
while (*from != '\0')
{
// *to = *from;
// to++; from++;
*to++ = *from++;
}
*to = '\0';
}
//上面函数继续优化
void copy_str4(char *from, char *to)
{
while ((*to++ = *from++) != '\0') ;
}
void main()
{
char from;
charto;
strcpy_s(from, "adadada123");
copy_str4(from, to);
printf("%s", to);
system("pause");
}
2、两头堵模型
#include "stdlib.h"
#include "stdio.h"
#include "string.h"
//两头堵，去除两边的空格，得出中间字符串的长度
int trispace(char * inbuf, char *outbuf)
{
int count = 0, ret = 0;
int i = 0, j = 0;
char *p = inbuf;
j = strlen(p) - 1;
//浮动指针查找关键位置
while (p == ' ' && p != '\0')
{
i++;
}
while (p == ' ' && j > 0)
{
j--;
}
count = j - i + 1;
printf("count:%d\n", count);
memcpy(outbuf, inbuf + i, count);
outbuf = '\0';
return ret;
}
voidmain()
{
int ret = 0;
char bu = NULL;
//char *p = " abcdefg ";
char buf[] = " abcdefg ";
char buf2;
ret = trispace(buf, buf2);
if (ret != 0)
{
printf("fun Error: code %d", ret);
}
printf("buf2:%s", buf2);
system("pause");
}
3、字符串反转模型
#include "stdlib.h"
#include "stdio.h"
#include "string.h"
//求取已知字符串的反序
void main()
{
char c;
//char *str;
char str[] = "abcdefg";
int len = strlen(str);
char *p1 = str;
char *p2 = str + len - 1;
//利用首尾指针取*不断交换
while (p1 < p2)
{
c = *p1;
*p1 = *p2;
*p2 = c;
p1++;
p2--;
}
printf("str:%s\n", str);
system("pause");
}
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