2 输入一个表示整数的字符串， 把该字符串转换成整数并输出。例如输入字符串"1234"，则输出整数1234

/*
输入一个表示整数的字符串，
把该字符串转换成整数并输出。例如输入字符串"1234"，则输出整数1234
*/

#include <iostream>
#include<stdio.h>
#include<math.h>
using namespace std;

int strToint(string &a);
int main()
{
	string input;
	cin >> input;
	cout << strToint(input) << endl;
	system("pause");
	return 0;
}

//实现字符串转成整数的函数
int strToint(string &a)
{
	int output = 0;
	int temp = 0;
	for (int i = 0; i < a.size(); i++)
	{
		if (a[i] == '0')
			temp = 0;
		else if(a[i] == '1')
			temp = 1;
		else if(a[i] == '2')
			temp = 2;
		else if(a[i] == '3')
			temp = 3;
		else if(a[i] == '4')
			temp = 4;
		else if(a[i] == '5')
			temp = 5;
		else if(a[i] == '6')
			temp = 6;
		else if(a[i] == '7')
			temp = 7;
		else if(a[i] == '8')
			temp = 8;
		else if(a[i] == '9')
			temp = 9;
		output += temp * pow(10, (a.size() - 1 - i));
	}
	return output;
}