C++中int型與string型互相轉換

像是C#,java等高級語言中,int轉String類型都是很簡單的,但是C++中比較麻煩：

 int 轉換string

 string int2str( int num)

 {

    if (num == 0 )

       return " 0 " ;                                                                                                                                      

    string str = "" ;

    int num_ = num > 0 ? num : - 1 * num;

    while (num_)

    {

       str = ( char )(num_ % 10 + 48 ) + str;

       num_ /= 10 ;

    }

    if (num < 0 )

       str = " - " + str;

    return str;

}

string 轉換int

 int str2int( string str)

 {

    int i,len = str.size(),num = 0 ;

    i = 0 ;  

    if (str[ 0 ] == ' - ' )

       i = 1 ;

    while (i < len)

    {

       num = num * 10 + ( int )(str[i] - ' 0 ' );

       i ++ ;                                                                                                                                               

    }

    if (str[ 0 ] == ' - ' )

       num *= - 1 ;

    return num;

}