string转化成int

来源：互联网发布：mysql use index 编辑：程序博客网时间：2024/05/16 15:28

上一篇列举了把int转成string的方法，这篇列举把string如何转成int，以及除了调用已有的API，如何自己写方法来进行转换。

#include "stdafx.h"

#include <iostream>

using namespace std;

#define CALL(namespace, method) \

cout << "Calling " #namespace"::" #method":"<< endl;\

method;\

}

#pragma region Convertstring to

namespace SC

{

string s = "199";

string sf = "199.9";

int i;

float f;

// C++ 11: stoi

#include <string>

void TestStoi()

{

i = stoi(s);

cout << i << endl;

f = stof(sf);

cout << f << endl;

}

// stringstream

#include <sstream>

void TestSStream()

{

stringstream stream;

stream << s;

stream >> i;

cout << i << endl;

}

// C: atoi

#include <stdlib.h>

void TestAtoi()

{

i = atoi(s.c_str());

cout << i << endl;

f = atof(sf.c_str());

cout << f << endl;

}

// Write custommethod

void TestCustomMethod()

{

const char* temp =s.c_str();

int sign = 1, result = 0;

if (*temp == '+')

temp++;

else if (*temp =='-')

{

temp++;

sign = -1;

}

while (*temp)

{

result = result * 10 +*temp - '0';

temp++;

}

result *= sign;

cout << result << endl;

}

// Boostlexical_cast

#include <boost/lexical_cast.hpp>

void TestBoostLexicalCast()

{

cout << boost::lexical_cast<int>(s)<< endl;

}

// strtol

void TestStrtol()

{

cout << static_cast<int>(strtol(s.c_str(),nullptr, 10))<< endl;

}

// sscanf

void TestSScanf()

{

sscanf_s(s.c_str(), "%d", &i);

cout << i << endl;

}

void TestConvertStringTo()

{

CALL(SC, TestStoi());

CALL(SC, TestSStream());

CALL(SC, TestAtoi());

CALL(SC, TestCustomMethod());

CALL(SC, TestBoostLexicalCast());

CALL(SC, TestStrtol());

CALL(SC, TestSScanf());

}

#pragma endregion

#define USE(name)usingnamespace name

#define TEST(namespace, method) \

USE(namespace);\

method;\

}

int main()

{

TEST(SC, TestConvertStringTo());

return 0;

}

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