This question already has answers here:
scanf format specifier to only read a number
(2 answers)
Closed 7 years ago.
How do you propose I write my code to accept only integers in C and if a letter is entered, prompt to enter only integers? And Vice versa.
printf("Enter integer");
scanf("%d", &a);
while(scanf("%d", &a)==0) //if scanf failed to scan an integer
{
printf("Invalid input. Try again\n");
int c;
while((c=getchar())!='\n' && c!=EOF); //clear the stdin
}
Related
This question already has answers here:
scanf() leaves the newline character in the buffer
(7 answers)
How to do scanf for single char in C [duplicate]
(11 answers)
abnormal behavior of scanf [duplicate]
(3 answers)
Closed 4 months ago.
int userinput;
char convertfrom;
float value;
printf("What do you want to convert? Enter number from 1 to 5: ");
scanf("%d", &userinput);
if (userinput == 1) {
printf("enter letter K or P: ");
scanf("%c\n", &convertfrom);
printf("letter = %c", convertfrom);
}
I input "P" for the second scanf that asks for a letter, but the code keeps failing to print "letter = P". instead it only prints "letter = ".
Why can't I print the user input?
This question already has answers here:
Program doesn't wait for user input with scanf("%c",&yn);
(5 answers)
scanf() leaves the newline character in the buffer
(7 answers)
Closed 1 year ago.
int main()
int c,s;
char h;
printf("Enter the carbon\n");
scanf("%d",&c);
printf("Enter the hard\n");
scanf("%c",&h);
printf("Enter strength\n");
scanf("%d",&s);
printf("%d%d",c,s);
printf("%c",h);
}
Output:
Enter the carbon
4
Enter the hard
Enter strength
My program is not reading character data types. Can anyone tell me the reason?
The compiler is not showing any error.
This question already has answers here:
scanf() leaves the newline character in the buffer
(7 answers)
How to read / parse input in C? The FAQ
(1 answer)
Closed 2 years ago.
So, i just want to know how to deal with this, the code doesnt have a purpose besides testing.
why does the the enter i press go to the getchar()command?
or is that the case to begin with? i assume it is.
here is the code
#include<stdio.h>
int main(){
int x,y,z;
printf("Enter two nums\n");
scanf("%d %d", &x, &y);
z=x/y;
printf("%d is answ\n", z);
puts("Press enter to exit");
getchar();
return 0;
}
This question already has answers here:
What is the effect of trailing white space in a scanf() format string?
(4 answers)
Simple C scanf does not work? [duplicate]
(5 answers)
Closed 4 years ago.
I wrote this code for a school project and I have the following problem.
When I choose 1 at the first time, my program runs fine but as I choose w or r the second time, something goes wrong. None of the 2 ifs is running. I printed usr_ans2 to see the result of scanf and usr_ans2 variable is a weird question mark in a box and not a w or r character as I typed. Also I tried scanf(" %c", usr_ans2) . The question marks do not appear but the if commands are still not running.
int main(){
int usr_ans1;
char usr_ans2;
while(1){
printf("\nSelect action: (1-3)\n");
scanf("%d", &usr_ans1);
if(usr_ans1 == 1){
printf("Select to write or read from a file the text: (w/r) ");
usr_ans2 = scanf("%c", &usr_ans2);
if(usr_ans2 == 'w')
printf("You selected to write");
else if(usr_ans2 == 'r')
printf("You selected to read");
}
else if(usr_ans1 == 2){
printf("Example1");
}
else if(usr_ans1 == 3){
printf("Example2");
}
return 0;
}
scanf() in usr_ans2 = scanf("%c", &usr_ans2); will return 1 (the numbers of successfully converted specifiers) or EOF (some negative value like -1 when end-of-file or error occurs). if(usr_ans2 == 'w') will never be true.
Try
// usr_ans2 = scanf("%c", &usr_ans2);
scanf(" %c", &usr_ans2); // add the space too to skip leading white-space
This question already has answers here:
How to clear input buffer in C?
(18 answers)
Why is scanf() causing infinite loop in this code?
(16 answers)
Closed 5 years ago.
I have this code, a program to take an integer from a user that's negative, if not trap them in a loop until they enter a negative integer. I have this part down, however, how could i clear the input buffer?
I tried to use while ((getchar()) != ‘\n’); after the first scanf_s but it fails.
here is code
#include <stdio.h>
int main()
{
int num;
printf("Please enter a negative integer");
scanf_s("%d", &num);
while (num >= 0.0)
{
printf("Please enter a negative integer!\n");
scanf_s("%d", &num);
}
printf("%d", num);
system("pause.exe");
return 0;
}