1. WIKI教程
2. C ++标准库
3. compare

compare

描述 (Description)

它将字符串对象（或子字符串）的值与其参数指定的字符序列进行比较。

声明 (Declaration)

以下是std :: string :: compare的声明。

int compare (size_t pos, size_t len, const string& str) const;
int compare (size_t pos, size_t len, const string& str,
             size_t subpos, size_t sublen) const;

C++11

int compare (size_t pos, size_t len, const string& str) const;
int compare (size_t pos, size_t len, const string& str,
             size_t subpos, size_t sublen) const;

C++14

int compare (size_t pos, size_t len, const string& str) const;
int compare (size_t pos, size_t len, const string& str,
             size_t subpos, size_t sublen = npos) const;

参数 (Parameters)

• str - 它是一个字符串对象。

• len - 用于复制字符。

• pos - 要复制的第一个字符的位置。

返回值 (Return Value)

它返回一个有符号的整数，表示字符串之间的关系。

异常 (Exceptions)

如果抛出异常，则字符串中没有变化。

例子 (Example)

在下面的示例中，std :: string :: compare。

#include <iostream>
#include <string>
int main () {
   std::string str1 ("green mango");
   std::string str2 ("red mango");
   if (str1.compare(str2) != 0)
      std::cout << str1 << " is not " << str2 << '\n';
   if (str1.compare(6,5,"mango") == 0)
      std::cout << "still, " << str1 << " is an mango\n";
   if (str2.compare(str2.size()-5,5,"mango") == 0)
      std::cout << "and " << str2 << " is also an mango\n";
   if (str1.compare(6,5,str2,4,5) == 0)
      std::cout << "therefore, both are mangos\n";
   return 0;
}

样本输出应该是这样的 -

green mango is not red mango
still, green mango is an mango
and red mango is also an mango
therefore, both are mangos