如何将一个 int 拼接在一个 string 上

std::string name = "John";
int age = 21;

std::string name = "John";
int age = 21;
std::string result;

// 1. with C++11
result = name + std::to_string(age);

// 2. with IOStreams
std::stringstream sstm;
sstm << name << age;
result = sstm.str();

// 3. with itoa
char numstr[21]; // enough to hold all numbers up to 64-bits
result = name + itoa(age, numstr, 10);

// 4. with sprintf
char numstr[21]; // enough to hold all numbers up to 64-bits
sprintf(numstr, "%d", age);
result = name + numstr;