字符串函数

<p style="margin-top: 0px; margin-bottom: 0px; font-size: 24px; font-family: Menlo; color: rgb(255, 255, 255);"><pre name="code" class="cpp">#include <stdio.h>
#include "MyString.h"
#include <stdlib.h>
///  输出字符串
void putString(const char *src)
{
    //printf("%s\n", src);
    while (*src) {
        printf("%c", *(src++));
    }
    printf("\n");
}
/// 计算字符串长度
unsigned long stringLength( const char *src)
{
    unsigned long int length = 0;
    
    while (*src++) {
        length++;
        
    }
    
    return  length;
    
}
///  拷贝字符串
char *stringCopy(char *dest,const char *src)
{
    char *p = dest;
    while ((*p++ = *src++)) {
        
    }
    return  dest;
}
///字符串拼接
char *stringCat(char *dest,const char *src)
{

    stringCopy(dest + stringLength(dest), src);//目的地址指向不变 v 没有自加
    
    return dest;
  
}
//字符串比较
int stringCompare( const char *s1,const char *s2)
{

    int result = 0;
    while (0 == (result = *s1 - *s2) && *s1) {
        s1++;
        s2++;
    }
    return result;
    
}
char * strCopy(const char *src)
{
     char  * dest = malloc(sizeof(char) * (stringLength(src) + 1));//堆如何使用
    stringCopy(dest, src);
    return  dest;//  野指针 指针指向了一段释放的内存   全局静态是不可释放的
}
char *numberString(const char *src)
{
    char *dest = malloc(sizeof(char) *(stringLength(src) + 1));
    char *p = dest;
    while (*src) {
        if (*src >= '0' && *src <= '9') {
            {
                *p = *src;
                p++;
            }
        }
        src++;
    }
   *p = '\0';
    return  dest;
}