string 转换为int

1.atoi

#include
using namespace std;
int main()
{
	int x = 0;
	string str1 = "10";
	string str2 = "-10";
	string str3 = "10a";
	x = atoi(str1.c_str());
	cout << x << endl;
	x = atoi(str2.c_str());
	cout << x << endl;
	x = atoi(str3.c_str());
	cout << x << endl;
	return 0;
}
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2.strtol

long int strtol (const char str, char* endptr, int base);

str 为要转换的字符串，endstr 为第一个不能转换的字符的指针，base 为字符串 str 所采用的进制。

 #include
using namespace std;
int main()
{
	int x = 0;
	string str1 = "10";
	string str2 = "-10";
	string str3 = "10a";
	x = strtol(str1.c_str(), nullptr, 10);
	cout << x << endl;
	x = strtol(str2.c_str(), nullptr, 10);
	cout << x << endl;
	x = strtol(str3.c_str(), nullptr, 10);
	cout << x << endl;

	return 0;
}

 
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3.stoi

c11之后才有，需要引入 < string>

#include
#include
using namespace std;
int main()
{
	int x = 0;
	string str1 = "10";
	string str2 = "-10";
	string str3 = "10a";
	x = stoi(str1);
	cout << x << endl;
	x = stoi(str2);
	cout << x << endl;
	x = stoi(str3);
	cout << x << endl;

	return 0;
}
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4. stringstream

需要引入< sstream>

#include
#include
using namespace std;
int stringToInt(const string& s)
{
	stringstream ss;
	int result;
	ss << s;
	ss >> result;
	return result;

}
int main()
{
	    string str1 = "10";
	    string str2 = "-10";
	    string str3 = "10a";
		cout << stringToInt(str1)<<endl;
		cout << stringToInt(str2)<<endl;
		cout << stringToInt(str3)<<endl;
	
}
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int 转换为string

1.sprintf_s

#include
using namespace std;
int main()
{
	int number = 10;
	char buff[128] = { 0 };
	sprintf_s(buff, 128, "%d",number);
	cout << buff << endl;

}
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2.stringstream

需要引入

#include
#include
using namespace std;
int main()
{
	int number = 10;
	stringstream ss;
	ss << number;
	string str = ss.str();
	cout << str << endl;

};
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3.to_string

c11之后才可用，需引入string

#include
#include
using namespace std;
int main()
{
	int number = 10;
	string str =to_string(number);
	cout << str << endl;

};
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