Data validation

I'm writting a progrm in which I want to verify the user doesn't input incoherent data. When I code this:

Code:

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#include<stdio.h>;
#include<conio.h>;
main(){
float var1;
clrscr();
scanf("%f",&var1);
printf("\n\n%f",var1);
}

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What happens is, if the user enters a valid float value I get the same float value on the output (duh). If he enters a character or a string I always get the same output whatever the input, that is: 149709439917360000.0000 . My question is, how does the computer get this value? Does it convert the characters into ASCII and multiply them or what? :confused: Thank you...

scanf() will convert all keys typed to float until the first non-digit (and +/- keys) key is typed. So if you type "12.34abc", scanf() will stop converting when it sees the letter 'a' was typed. The rest of the keys remain in the keyboard.

Ok, so if I type 12.34abc var1 gets the value 12.34. Check. Now, if I type in abc12.34 how does var1 come to get the value 1443268871235100000.0000 whatever....?

In that case, scanf() will not change the value of var1 -- the number you posted appears because you didn't initialize the varaible with anything. Set it to 0 when declared and you will see the difference. YOu also should check the return value of scanf() to see how many variables were processed or if there was a conversion error. In your example, scanf will most likely return 0 because no variables were converted.

Code:

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#include<stdio.h>;

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You shouldn't have semicolons after #includes.