首先声明我的确时一个新手,一个substr()函数让我的一个项目功能出现了问题。
先给一下msdn上的内容要求吧。
其功能是 Copies a substring of at most some number of characters from a string beginning from a specified position.
内部定义的函数是:
basic_string substr( size_type _Off = 0, size_type _Count = npos ) const;
解释一下参数吧,这里有两个参数,第一个参数是要截取的字符串的起始位置,后一个参数是要截取字符串的长度。
返回值:Return Value
A substring object that is a copy of elements of the string operand beginning at the position specified by the first argument.
例子:
// basic_string_substr.cpp // compile with: /EHsc #include <string> #include <iostream> int main( ) { using namespace std; string str1 ("Heterological paradoxes are persistent."); cout << "The original string str1 is: \n " << str1 << endl << endl; basic_string <char> str2 = str1.substr ( 6 , 7 ); cout << "The substring str1 copied is: " << str2 << endl << endl; basic_string <char> str3 = str1.substr ( ); cout << "The default substring str3 is: \n " << str3 << "\n which is the entire original string." << endl; }
输出结果是
The original string str1 is: Heterological paradoxes are persistent.
The substring str1 copied is: logicalThe default substring str3 is: Heterological paradoxes are persistent.
which is the entire original string.