我原以为这很简单,但它出现了一些困难。如果我有
std::string name = "John";
int age = 21;
我如何结合他们得到一个单一的字符串“John21”?
我原以为这很简单,但它出现了一些困难。如果我有
std::string name = "John";
int age = 21;
我如何结合他们得到一个单一的字符串“John21”?
当前回答
#include <sstream>
template <class T>
inline std::string to_string (const T& t)
{
std::stringstream ss;
ss << t;
return ss.str();
}
那么你的用法应该是这样的
std::string szName = "John";
int numAge = 23;
szName += to_string<int>(numAge);
cout << szName << endl;
谷歌[并测试:p]
其他回答
我写了一个函数,它以int数作为参数,并将其转换为字符串字面量。此函数依赖于另一个函数,该函数将单个数字转换为其char等价:
char intToChar(int num)
{
if (num < 10 && num >= 0)
{
return num + 48;
//48 is the number that we add to an integer number to have its character equivalent (see the unsigned ASCII table)
}
else
{
return '*';
}
}
string intToString(int num)
{
int digits = 0, process, single;
string numString;
process = num;
// The following process the number of digits in num
while (process != 0)
{
single = process % 10; // 'single' now holds the rightmost portion of the int
process = (process - single)/10;
// Take out the rightmost number of the int (it's a zero in this portion of the int), then divide it by 10
// The above combination eliminates the rightmost portion of the int
digits ++;
}
process = num;
// Fill the numString with '*' times digits
for (int i = 0; i < digits; i++)
{
numString += '*';
}
for (int i = digits-1; i >= 0; i--)
{
single = process % 10;
numString[i] = intToChar ( single);
process = (process - single) / 10;
}
return numString;
}
这个问题可以用许多方法解决。我将以两种方式展示它:
Convert the number to string using to_string(i). Using string streams. Code: #include <string> #include <sstream> #include <bits/stdc++.h> #include <iostream> using namespace std; int main() { string name = "John"; int age = 21; string answer1 = ""; // Method 1). string s1 = to_string(age). string s1=to_string(age); // Know the integer get converted into string // where as we know that concatenation can easily be done using '+' in C++ answer1 = name + s1; cout << answer1 << endl; // Method 2). Using string streams ostringstream s2; s2 << age; string s3 = s2.str(); // The str() function will convert a number into a string string answer2 = ""; // For concatenation of strings. answer2 = name + s3; cout << answer2 << endl; return 0; }
常见答案:itoa()
这很糟糕。正如这里指出的,Itoa是非标准的。
std:: ostringstream
<sstream>#include std::ostringstream s; 与<<“约翰”<<年龄; std::string query(s.str());
std:: to_string (C + + 11)
std::string查询("John " + std::to_string(年龄));
boost:: lexical_cast
# include <刺激/ lexical_cast.hpp > std::string查询("John " + boost::lexical_cast<std::string>(age));
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
string itos(int i) // convert int to string
{
stringstream s;
s << i;
return s.str();
}
无耻地从http://www.research.att.com/~bs/bs_faq2.html窃取。