C 知识点(3)

记录了字符数组和字符串的几个易错知识点

字符数组和字符串

字符串中值无法改变

#include <stdio.h>
int main()
{
    char *p = "abcdef";
    p[0] = 'm';
    return 0;
}

以上代码会报错，无法直接修改字符串的值。

---

求长度、拷贝功能实现

#include <stdio.h>


//字符串求长度
int myStrlen(const char *src)
{
    int len = 0;
    while (*src != '\0') {
        len++;
        src++;
    }
    return len;
}


//字符串拷贝
char * myStrcpy(char *dest,char *src)
{
    char *retDest = dest;
    while ((*dest = *src)!='\0') {
        dest++;
        src++;
    }
    return retDest;
}


int main(void)
{

    char str[] = "Test test";
    int len = myStrlen(str);
    printf("len of str  =  %d\n",len);


    char dest[100];
    char src[100]="Test StringCpy";
    char anotherDest[100];

//    myStrcpy(dest, src);

    myStrcpy(anotherDest,myStrcpy(dest, src));
    printf("dest = %s\n",dest);
    printf("anotherDest = %s\n",anotherDest);
    return 0;
}

运行结果

len of str  =  9
dest = Test StringCpy
anotherDest = Test StringCpy