Handling int num1 = 'a';

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Calculate addition of two integers and print output.

Sample input: 3 and 1
Sample Output: 4

Sample input: 'a' and 'b'
Sample output: invalid input

And sample input should be hardcoded and should display as given above

Finally i don't know how to handle such condition please help

What I have tried:

I have tried ASCII comparison to distinguish between int value and char value.

Posted 7-Jun-16 4:22am

Rahul Thengadi

Updated 7-Jun-16 5:45am

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CHill60 7-Jun-16 10:25am

The "What I have tried" section is for you to put the code that you have tried.
Are you aware of the isdigit function? isdigit - C++ Reference[^]

Rahul Thengadi 7-Jun-16 10:31am

As the int num1 = 'a';
Here num1 = 97 // ASCII value of 'a'
isdigit can't handle it

CHill60 7-Jun-16 10:58am

If you want to reply to a comment use the "Reply" link so that the poster is notified of your response.
isdigit can handle 'a' - there is absolutely no need to get the ascii value of 'a'!

Rahul Thengadi 7-Jun-16 11:11am

#include<iostream>

using std::cout;
using std::cin;
using std::endl;

int add(int num1,int num2)
{
if(isdigit(num1) != 0 && isdigit(num2) != 0)
{
cout << num1+num2;
}
else
cout << "Error" << endl;
}

int main()
{
int num1 = 3;
int num2 = 1;

add(num1,num2);

num1 = 'a'; // here num1 value is 97 i.e. ASCII value of character a
num2 = 'b'; // here num1 value is 97 i.e. ASCII value of character a

add(num1,num2);

return 0;
}

Output: Error
Error

Rahul Thengadi 7-Jun-16 15:35pm

Thanks , the validNum() is much useful, i was nearly close to the answer

Rahul Thengadi 7-Jun-16 17:12pm

I tried your solution, it ended up with input(3,1)=>output(4) and for input('a','b')=>output(195)

CHill60 8-Jun-16 5:07am

if you got output 195 for inputs 'a','b' then it wasn't my solution - I did test mine for many input values. Note my comment below - if you are replacing stoi() with the equivalent for your compiler it should NOT be getting the ascii value. In fact 'a' and 'b' should not be passing the ValidNum() test

Rahul Thengadi 8-Jun-16 5:57am

Ya i will try one more time as soon as new version of g++ compiler is installed on my pc.
The old compiler wasn't supporting 'stoi' so i tested that program on codechef online ide.

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LLLLGGGG · Answer 1 · 2016-06-07T04:45:00

Maybe you want something like this:

C++

#include<cstdlib>
#include<iostream>
#include<limits>
using namespace std;

int main(){
	cout << "Insert a number -> ";
	int a;
	while((cin >> a).fail()){
	    cout << "Bad value!";
	    cin.clear();
	    cin.ignore(numeric_limits<streamsize>::max(), '\n');
	}
	cout << "The number is -> " <<a <<endl;
	system("PAUSE");
	return 0;
}
</streamsize></limits></iostream></cstdlib>

The program above just displays the number a, you need to modify it a little to get it to work with the sum of two numbers.

How does it work
cin.fail() returns true if it fails to extract data from the input that can go inside the given variable (in this case, a). If it fails, cin.clear() resets the state of the error flag and cin.ignore(numeric_limits<streamsize>::max(), '\n')</streamsize> ignores the wrong input.

Hope this helps.

CHill60 · Answer 2 · 2016-06-07T05:45:00

Here is my justification for my comments above where I say isdigit will work (when it is used properly).

In this case you have

Quote:
And sample input should be hardcoded and should display as given above

In most cases (or as you move through your course) inputs will come from the command line (or parameters) in which case it is safe to assume any key can be used ... so handle strings.
Lusvardi has given a good example of how to do this.

My snippet below is intended to show you how isdigit would work in this instance - see the function ValidNum

C++

#include<iostream>
#include<string>
using namespace std;

void ProcessSample(string num1, string num2);
bool ValidNum(string num);
void OutputResult(int num1, int num2);

void main(){

	//Sample input is hardcoded - should really be a loop of input

	//Sample input: 3 and 1 : Expected Output: 4
	ProcessSample("3","1");

	//Sample input: 'a' and 'b' : Expected Output 'Invalid input'
	ProcessSample("a","b");

	//Sample input: '1' and 'b' : Expected Output 'Invalid input'
	ProcessSample("1","b");

	//Sample input: 23 and 101 : Expected Output: 124
	ProcessSample("23","101");

	cout << "Hit a key to end";
	getchar();

	return;
}
void ProcessSample(string num1, string num2)
{
	if(ValidNum(num1) && ValidNum(num2))
		cout << "Result: " << stoi(num1) + stoi(num2) << endl;
	else
		cout << "Invalid Input" << endl;
}
// Validates that the input represents a number
// Should handle any number of digits up to MAXINT in length
bool ValidNum(string num)
{
	bool ret = true;
	for(int i = 0; i < num.length(); i++)
		if(!isdigit(num[i])) ret = false;
	return ret;
}

Handling int num1 = 'a';

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