如何判断输入的数据是整型还是字符型？
#include <iostream>#include <string>using namespace std;char continueWorking ();char ch;void main (){ char operation; char FirstNumber[100]; int SecondNumber; do { cout << "Key in an operator: + - * /" << endl; cin >> operation; if (operation != '+' && operation != '-' && operation != '*' && operation != '/') { cout << "you enter a bad operation!" << endl; continue; } cout << "enter the first number:" << endl; cin >> FirstNumber; for (int j=0; j<strlen(FirstNumber); j++)//如何判断用户输入的是字符还是整型数据呢? { if ((int)FirstNumber[j] < 0 || (int)FirstNumber[j] > 9) { cout << "date error !" << endl; } break; }//这个循环有错误！当输入整数的时候，却没有break?!!!!应该如何改正呢？ cout << "enter the second number:" << endl; cin >> SecondNumber; switch (operation) { case '+': cout << FirstNumber + SecondNumber << endl; break; case '-': cout << FirstNumber - SecondNumber << endl; break; case '*': cout << (int)FirstNumber * SecondNumber << endl; break; case '/': cout << (int)FirstNumber / SecondNumber<< endl; break; default: break; } }while (continueWorking () == 'y');}char continueWorking (){ do { cout << "Would you like to continue ? (y / n)" << endl; cin >> ch; }while (ch != 'y' && ch != 'n'); return ch;}#include <iostream>#include <string>using namespace std;char continueWorking ();bool isInteger(const char* str);char ch;void main (){ char operation; char FirstNumber[100]; int SecondNumber; do { cout << "Key in an operator: + - * /" << endl; cin >> operation; if (operation != '+' && operation != '-' && operation != '*' && operation != '/') { cout << "you enter a bad operation!" << endl; continue; } cout << "enter the first number:" << endl; cin >> FirstNumber; if ( !isInteger(FirstNumber) ) continue; cout << "enter the second number:" << endl; cin >> SecondNumber; int first = atoi(FirstNumber); switch (operation) { case '+': cout << first + SecondNumber << endl; break; case '-': cout << first - SecondNumber << endl; break; case '*': cout << first * SecondNumber << endl; break; case '/': cout << first / SecondNumber<< endl; break; default: break; } }while (continueWorking () == 'y');}char continueWorking (){ do { cout << "Would you like to continue ? (y / n)" << endl; cin >> ch; }while (ch != 'y' && ch != 'n'); return ch;}bool isInteger(const char* str){ bool isInt = true; for (int j=0; j<strlen(str); j++)//如何判断用户输入的是字符还是整型数据呢? { if ( str[j] < '0' || str[j] > '9') { cout << "date error !" << endl; isInt = false; break; } }//这个循环有错误！当输入整数的时候，却没有break?!!!!应该如何改正呢？ return isInt;}