how to strict the user to just enter a number when the programme ask about the input or just how to apply numeric input on a entry can anyone help me out.
as a exmpale:
#include "stdio.h"
#include "conio.h"
void main()
{
int x;
printf("Enter a numeric value:");
scanf("%d",&x);
if(..........) // here i supose to write the if statement
}
scanf returns the number of parameters successfully processed, so you need to store its return value and test that.
Therefore, you can do if (scanf("%d", &x)) { ... } else {... } instead, since scanf will either return 0 (no integer was matched) or 1 (if an integer was matched)
EDIT
if (scanf("%d", &x)) {
/* an integer was read into x, so what do you want to do here? */
} else {
/* what the user typed was not an integer, so normally you want to write some error message or something */
}
You should receive the whole line which inputed by user, then use isdigit()(defined in ctype.h) to check each charactor to see if it is a number.
isdigit despite the C standard requiring it to return nonzero if and only if ((unsigned)c-'0'<10).
I advise you to check here: http://www.tek-tips.com/viewthread.cfm?qid=1024751&page=10
Interestingly enough, that is also the first result on Google.
Also, stop using void main(). It's restricting.
Also, consider taking input in a infinite while loop, and break out of it when the user enters the proper input.
If you want the user's input to satisfy a certain condition, you can do something like this:
#include <stdio.h>
int main()
{
int x;
printf("Enter a numeric value:");
scanf("%d", &x);
//suppose you want the user to enter values b/w 0 and 999
while ((x < 0) || (x >= 1000)) {
scanf("%d", &x);
}
}
Remember, void main and conio.h are not standard compliant.
