C++ std::memcmp()用法及代码示例

它比较buf1和buf2指向的数组的第一个计数字符。
用法:

int memcmp(const void *buf1, const void *buf2, size_t count);
返回值： it returns an integer.
参数：  
buf1: Pointer to block of memory.
buf2: Pointer to block of memory.
count: Maximum numbers of bytes to compare.
Return Value is interpreted as:
Value                                Meaning
Less than zero                       buf1 is less than buf2.
Zero                                 buf1 is equal to buf2.
Greater than zero                    buf1 is greater than buf2.

例子1.当计数大于零(> 0)

// CPP program to illustrate std::memcmp() 
#include <iostream> 
#include <cstring> 
  
int main() 
{ 
    char buff1[] = "Welcome to GeeksforGeeks"; 
    char buff2[] = "Hello Geeks "; 
  
    int a; 
  
    a = std::memcmp(buff1, buff2, sizeof(buff1)); 
  
    if (a > 0) 
        std::cout << buff1 << " is greater than " << buff2; 
    else if (a < 0) 
        std::cout << buff1 << "is less than " << buff2; 
    else
        std::cout << buff1 << " is the same as " << buff2; 
  
    return 0; 
}

输出：

Welcome to GeeksforGeeks is greater than Hello Geeks

例子2.当计数小于零(<0)

// CPP program to illustrate std::memcmp()  
#include <cstring> 
#include <iostream> 
  
int main() 
{ 
    int comp = memcmp("GEEKSFORGEEKS", "geeksforgeeks", 6); 
    if (comp == 0) { 
        std::cout << "both are equal"; 
    } 
    if (comp < 0) { 
        std::cout << "String 1  is less than String 2"; 
    } else { 
        std::cout << "String 1 is  greater than String 2"; 
    } 
}

输出：

String 1 is less than String 2

示例3：当计数等于零(= 0)时

// CPP program to illustrate std::memcmp() 
#include <iostream> 
#include <cstring> 
  
int main() 
{ 
    char buff1[] = "Welcome to GeeksforGeeks"; 
    char buff2[] = "Welcome to GeeksforGeeks"; 
  
    int a; 
  
    a = std::memcmp(buff1, buff2, sizeof(buff1)); 
  
    if (a > 0) 
        std::cout << buff1 << " is greater than " << buff2; 
    else if (a < 0) 
        std::cout << buff1 << "is less than " << buff2; 
    else
        std::cout << buff1 << " is the same as " << buff2; 
  
    return 0; 
}

输出：

Welcome to GeeksforGeeks is the same as Welcome to GeeksforGeeks

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注：本文由纯净天空筛选整理自 std::memcmp() in C++。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。