C++中的std :: memcmp()

它比较buf1和buf2指向的数组的第一个计数字符。
句法：

int memcmp(const void *buf1, const void *buf2, size_t count);
Return Value: it returns an integer.
Parameters:  
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 
#include 
  
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 
#include 
  
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 
#include 
  
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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