#include <iostream>
#include <cstring>

using namespace std;

/**
 * @brief myStrLen
 * @param str
 * @return str's length
 */
unsigned int myStrLen(char str[])
{
    int len = 0;

    for( ; *str; ++str) {
        ++len;
    }

    return len;
}

/**
 * @brief myStrLen1
 * @param str
 * @return str's length
 */
unsigned int myStrLen1(char str[])
{
    int len = 0;

    while(*str) {
        ++len;
        ++str;
    }

    return len;
}

/**
 * @brief myStrLen2
 * @param str
 * @return str's length
 */
unsigned int myStrLen2(char str[])
{
    return *str ? myStrLen2(++str)+1 : 0;
}

int main()
{
    char str[] = "I Love cpp";
    cout<<"----------------------------------------"<<endl;
    //strlen 不含'
 
 
代码实现
 
 
 
  
#include <iostream>
#include <cstring>

using namespace std;

/**
 * @brief myStrLen
 * @param str
 * @return str's length
 */
unsigned int myStrLen(char str[])
{
    int len = 0;

    for( ; *str; ++str) {
        ++len;
    }

    return len;
}

/**
 * @brief myStrLen1
 * @param str
 * @return str's length
 */
unsigned int myStrLen1(char str[])
{
    int len = 0;

    while(*str) {
        ++len;
        ++str;
    }

    return len;
}

/**
 * @brief myStrLen2
 * @param str
 * @return str's length
 */
unsigned int myStrLen2(char str[])
{
    return *str ? myStrLen2(++str)+1 : 0;
}

int main()
{
    char str[] = "I Love cpp";
    cout<<"----------------------------------------"<<endl;
    //strlen 不含'\0'
    cout<<"str's length is: "<<strlen(str)<<"(c lib function)"<<endl;
    cout<<"str's length is: "<<myStrLen(str)<<"(for loop version)"<<endl;
    cout<<"str's length is: "<<myStrLen1(str)<<"(while loop version)"<<endl;
    cout<<"str's length is: "<<myStrLen2(str)<<"(recursive version)"<<endl;
    cout<<"----------------------------------------"<<endl;
    cout<<"sizeof str is:"<<sizeof(str)<<endl;  //sizeof 包含'\0'
    cout<<"----------------------------------------"<<endl;
    return 0;
}

 
  
 
   
 
  
 
  
运行结果
 
  
 
   
 
  
 
  
 
    
   
 
  
 
  
 
   
 
  
 
  
代码解析
 
  
 
   
 
  
 
  

    myStrLen()和myStrLen1()实现原理一样，都是通过循环移动字符指针，同时自增长度变量（len）直到遇到 '\0' 为止。myStrLen2()则是通过采用递归的方法，递归结束的条件是遇到字段串的结束符 '\0'。 
  
 
  
 
   
 
  
 
  
 
  
 
 
 
  
  

'
    cout<<"str's length is: "<<strlen(str)<<"(c lib function)"<<endl;
    cout<<"str's length is: "<<myStrLen(str)<<"(for loop version)"<<endl;
    cout<<"str's length is: "<<myStrLen1(str)<<"(while loop version)"<<endl;
    cout<<"str's length is: "<<myStrLen2(str)<<"(recursive version)"<<endl;
    cout<<"----------------------------------------"<<endl;
    cout<<"sizeof str is:"<<sizeof(str)<<endl;  //sizeof 包含'
 
 
代码实现
 
 
 
  
#include <iostream>
#include <cstring>

using namespace std;

/**
 * @brief myStrLen
 * @param str
 * @return str's length
 */
unsigned int myStrLen(char str[])
{
    int len = 0;

    for( ; *str; ++str) {
        ++len;
    }

    return len;
}

/**
 * @brief myStrLen1
 * @param str
 * @return str's length
 */
unsigned int myStrLen1(char str[])
{
    int len = 0;

    while(*str) {
        ++len;
        ++str;
    }

    return len;
}

/**
 * @brief myStrLen2
 * @param str
 * @return str's length
 */
unsigned int myStrLen2(char str[])
{
    return *str ? myStrLen2(++str)+1 : 0;
}

int main()
{
    char str[] = "I Love cpp";
    cout<<"----------------------------------------"<<endl;
    //strlen 不含'\0'
    cout<<"str's length is: "<<strlen(str)<<"(c lib function)"<<endl;
    cout<<"str's length is: "<<myStrLen(str)<<"(for loop version)"<<endl;
    cout<<"str's length is: "<<myStrLen1(str)<<"(while loop version)"<<endl;
    cout<<"str's length is: "<<myStrLen2(str)<<"(recursive version)"<<endl;
    cout<<"----------------------------------------"<<endl;
    cout<<"sizeof str is:"<<sizeof(str)<<endl;  //sizeof 包含'\0'
    cout<<"----------------------------------------"<<endl;
    return 0;
}

 
  
 
   
 
  
 
  
运行结果
 
  
 
   
 
  
 
  
 
    
   
 
  
 
  
 
   
 
  
 
  
代码解析
 
  
 
   
 
  
 
  

    myStrLen()和myStrLen1()实现原理一样，都是通过循环移动字符指针，同时自增长度变量（len）直到遇到 '\0' 为止。myStrLen2()则是通过采用递归的方法，递归结束的条件是遇到字段串的结束符 '\0'。 
  
 
  
 
   
 
  
 
  
 
  
 
 
 
  
  

'
    cout<<"----------------------------------------"<<endl;
    return 0;
}

#include <iostream>
#include <cstrin