C++ 整型与字符串的互转方式
flyfish
字符串转整型
C的方法 cstr是char*或者const char*类型的字符串
int num = atoi(str);
int num = strtol(cstr, NULL, 10);
//10 表示进制
C++11的方法
void test1()
{
std::string str1 = "1";
std::string str2 = "1.5";
std::string str3 = "1 with words";
int myint1 = std::stoi(str1);
int myint2 = std::stoi(str2);
int myint3 = std::stoi(str3);
std::cout << "std::stoi(\"" << str1 << "\") is " << myint1 << '\n';
std::cout << "std::stoi(\"" << str2 << "\") is " << myint2 << '\n';
std::cout << "std::stoi(\"" << str3 << "\") is " << myint3 << '\n';
}
结果输出
std::stoi(“1”) is 1
std::stoi(“1.5”) is 1
std::stoi(“1 with words”) is 1
//源码参考cplusplus.com
void test2()
{
std::string str_dec = "2001, A Space Odyssey";
std::string str_hex = "40c3";
std::string str_bin = "-10010110001";
std::string str_auto = "0x7f";
std::string::size_type sz; // alias of size_t
int i_dec = std::stoi (str_dec,&sz);
int i_hex = std::stoi (str_hex,nullptr,16);
int i_bin = std::stoi (str_bin,nullptr,2);
int i_auto = std::stoi (str_auto,nullptr,0);
std::cout << str_dec << ": " << i_dec << " and [" << str_dec.substr(sz) << "]\n";
std::cout << str_hex << ": " << i_hex << '\n';
std::cout << str_bin << ": " << i_bin << '\n';
std::cout << str_auto << ": " << i_auto << '\n';
return 0;
}
输出
2001, A Space Odyssey: 2001 and [, A Space Odyssey]
40c3: 16579
-10010110001: -1201
0x7f: 127
其他类型 类似
无符号整型
stoul
浮点型
stof
数值转字符串
std::string s;
s = std::to_string(1) + ” is int, “;
其他数值类型 类似
s = std::to_string(3.14f) + ” is float.”;
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