#include <iostream.h>
#include <stdlib.h>
int main()
{
int a;
while (a != 1) {
system("CLS");
std::cout << "Please enter 1" << std::endl;
std::cin >> a;
if (a >= 2 || a <= 0) {
std::cout << "Error...please enter 1!" << std::endl;
system("PAUSE");
}
}
std::cout << "Thank you!" << std::endl << std::endl;
system("PAUSE");
return 0;
}
handeling int's being put in as letters...
Author
right...so here is a code:
The simplest way is to synch the stream and clear all errors before reading.
std::cin.sync();std::cin.clear();if(std::cin >> a){ // valid input}else{ // invalid input}
Author
I don't get it...? what is that? I plugged it into the program both directly before and directly after the input but it still doesn't do anything...
thanks but...
-Ajain
thanks but...
-Ajain
I think what the anonymous poster was trying to say is that cin returns a bool. True means that the input was valid, false means that it is invalid. If you put the call cin in a conditional statement, you can test whether it was successful or not.
Instead of making a int, make it char. Now if you check the ASCII table you'll see that '1' equals 49.
Explanation: a char is actually a value converted to a sign by the console. So if you set a char to 49 without quotes it will become '1' as a character. But if you put 1 without quotes, you'll get SOH-character which is of no use.
In C++ you can check chars with singlequotes '1' or with the int-value which is 49.
Note: with character-strings (char*) it does not work. You'll need to use a function like atol() to convert the character-string to an integer. But in your example, you're only checking a single-digit number, so my above example should work in this case.
Explanation: a char is actually a value converted to a sign by the console. So if you set a char to 49 without quotes it will become '1' as a character. But if you put 1 without quotes, you'll get SOH-character which is of no use.
In C++ you can check chars with singlequotes '1' or with the int-value which is 49.
char a;cin >> a;if(a == '1' && a == 49) { // Yes! It rocks!}Note: with character-strings (char*) it does not work. You'll need to use a function like atol() to convert the character-string to an integer. But in your example, you're only checking a single-digit number, so my above example should work in this case.
Here's how I would do it.
char input;
int a = 0;
while(a != 1) {
...std::cin >> input; // Read character in. WARNING: the input should probably be a character array, to prevent more than one character being entered.
...a = atoi(input); // Convert first character to a number.
}
char input;
int a = 0;
while(a != 1) {
...std::cin >> input; // Read character in. WARNING: the input should probably be a character array, to prevent more than one character being entered.
...a = atoi(input); // Convert first character to a number.
}
1) include <iostream> and <cstdlib>. iostream.h is depreciated, and cstdlib is the C++ version of stdlib.h. (you will need to either fully qualify the namespace, or stick a using namespace std; right after the header includes)
2) you need to initialize a, right now it could contain anything, even a 1.
2) you need to initialize a, right now it could contain anything, even a 1.
#include <iostream>#include <cstdlib>#include <string>//this:using std::cin;using std::string;using std::system;//or this://using namespace std;int main() { int a = 0; //initialized to 0 while(a != 1) { while(!(cin>>a)) { //while the stream is not good (aka, they enter in a character) string chuckable; cin.clear(); //clears the error flags, returns the stream to a readable state cin>>chuckable; //will read up to the next whitespace. } //... your code here... }}This topic is closed to new replies.
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