How can I make scanf () to receive the value of b? - c

int a,b;
while (scanf("%d",&a) != EOF){
printf("%d ",a);
}
printf("\n");
printf("Pls enter value b\n");
scanf("%d",&b);
printf("%d",b);
return 0;
When I type and then use command + D to jump out of the while loop, I cannot enter it again at this time, resulting in the value of b being random.

As other have suggested , you should find another way to terminate your loop. Although , here is a workaround:
#include <stdio.h>
int main(){
int a,b;
while (scanf("%d",&a)!=EOF){
printf("%d ",a);
}
printf("\n");
printf("Pls enter value b\n");
freopen("/dev/tty", "r", stdin); /* Change /dev/tty to con: if you are using windows */
scanf("%d",&b);
printf("%d",b);
return 0;
}
You can use freopen to force input from the console.

I got a mail from IntelliJ , You can see it.
I type the links so that you can access link.
email-content:
There is an issue with sending EOF in CLion: https://youtrack.jetbrains.com/issue/CPP-5704. Disabling run.processes.with.pty is a workaround which helps to get the output printed after EOF. But this workaround has downsides like the one you faced with using scanf() after EOF. Unfortunately, there is no way to get both the output after EOF and scanf() after EOF working correctly until the issue (https://youtrack.jetbrains.com/issue/CPP-5704) is resolved. Feel free to comment or upvote the issue in order to get updates. See https://intellij-support.jetbrains.com/hc/en-us/articles/207241135-How-to-follow-YouTrack-issues-and-receive-notifications if you are not familiar with YouTrack.
Sorry for the inconvenience.
Best regards,
Anna Falevskaya
JetBrains
http://www.jetbrains.com
The Drive to Develop

Related

My command prompt wont run the whole program

This code runs perfectly in my IDE; I even tried it in an online compiler just to be sure, but when I try to open the .exe it will only ask for the integer and automatically close. I tried it with another program from the school where I asked for like 15 numbers but right before a goodbye message it just closes. Any idea how to fix cmd?
#include <stdio.h>
int main()
{
int numberOfWidgets;
printf("Give me a number: ");
scanf("%d", &numberOfWidgets);
printf("You choose the number: %d", numberOfWidgets);
return 0;
}
You need to add two lines to the end of your program:
int main() {
...
getchar();
getchar();
return 0;
}
The first call to getchar will clear the return key you pressed when you entered the number, the second one will stop and wait for a key to be pressed.
That way, your program will not exit until you press a key, and you will be able to read the output.

My Visual Studio Code won't run my code properly

I can't properly run/debug my code in VS Code using the C language. I've installed C/C++ package on VSC, Mingw & applied the path for Mingw. All my files are running .c format as well.
Only the last part of my code keeps crashing in VSC, when I run this same code on website compilers, it works!
Here is my code:
#include <stdio.h>
int main(void) {
int num1;
int num2;
printf("Enter a number: ");
scanf("%d", &num1);
printf("Enter another number: ");
scanf("%d", &num2);
printf("Answer: %d ", num1 + num2);
return 0;
}
That last printf is where VSC just shuts down the output window, so I never get to see the end result of my code. Anyone have any solutions to fix this? It'd be greatly appreciated!
When you run your console program from Visual Studio, it opens a terminal window, runs the program and the terminal window closes automatically when the program exits. This is a classic problem with the Microsoft Windows platform that they do not seem to care about despite millions of newbie programmers like you experiencing the same problem.
If you open the terminal window yourself, by running the CMD command from the start menu, you will be able to run your program manually after changing the current directory to that of the program binary.
To prevent the terminal window from closing immediately when running directly from Visual Studio, you should add 2 getchar(); statements before returning from main() to wait for user input and get a chance to see the output. Just reading a single byte with getchar() will not suffice because it will just read the pending newline entered by the user in response to the second prompt.
Also note that it is preferable to output a trailing newline to ensure the output is properly flushed on some legacy systems:
printf("Answer: %d\n", num1 + num2);
Here is a modified program you can test:
#include <stdio.h>
int main(void) {
int num1 = 0, num2 = 0;
printf("Enter a number: ");
scanf("%d", &num1);
printf("Enter another number: ");
scanf("%d", &num2);
printf("Answer: %d\n", num1 + num2);
getchar(); // read the pending newline
getchar(); // read at least another byte from the user.
return 0;
}
run you program from the console:
In the search box type cmd
cd \path_to_your_executable
run your program.

getchar() returns a character that isn’t a newline after I press enter

This is the code:
#include <stdio.h>
int main()
{
int i = 0;
while(getchar() != '\n') {
printf("\n%d\n", i);
i++;
}
printf("second printf: %d\n", i);
return 0;
}
The expected ouput after I press enter only is:
second printf: 0
instead of:
0
second printf: 1
Why is this happening ?
I am on linux Ubuntu MATE.
So I got some information about anas firari's environment by reading his other questions. This involves some measure of physic debugging.
You are getting input of \r\n when you type a newline because your terminal is in raw mode. Older shells used to choke on this by treating \r as something that isn't whitespace, but newer ones actually work ok.

Easy C: Program stuck after asking for prompt

In the following simple program after the user inputs an integer the command line remains a flashing prompt. When I exit the program the answer is then printed out. Why is this and how can I fix it?
//powers of 2
#include <stdio.h>
int main(void){
int a,b=1,i;
printf("What power of 2?\n");
scanf("%i\n",&a);
for (i=0; i<a;i++)
{
b=b*2;
}
printf("the answer is: %i\n",b);
return 0;
}
Try remove the \n in your scan :
scanf("%i",&a);
Remove \n from scanf. After that I compiled your program and it worked properly.

Using putchar and printf together in the same C Program?

I've written a small C program where I wanted to display the numeric ASCII value that corresponds to certain key presses.
My code follows. The problem is, after running the program, it accepts input, but doesn't do anything else. It doesn't even reach the first printf statement. I can't figure out what the issue is - is there a problem with mixing the getchar() function with the printf() function in the same program?
#include <stdio.h>
int main() {
const int numKeys = 256;
int keys[numKeys];
int i;
for (i = 0; i < numKeys; i++) {
keys[i] = 0;
}
printf("\n Start pressing some keys!\n\n");
int c;
while ((c = getchar()) != EOF) {
printf(" CAPTURED: %d\n", c);
keys[c]++;
}
printf("\n\n ** RESULTS ** \n\n");
for (i = 0; i < numKeys; i++) {
if (keys[i] != 0) {
printf(" Key with value %d was called %d times.", i, keys[i]);
}
}
}
I should clarify that I have a Windows XP Pro machine, with Cygwin installed. I use Cygwin for my development space, so I wonder if there is something different when running this type of program in that environment.
I found the problem. I think you want to use
while ((c = getchar()) != EOF && c != '\n')
Instead if you want to have it print the results after the person hits enter/return.
problem 1 : getting to printf(" CAPTURED: %d\n", c); without having to press the Enter key
solution : is by using getche() in while loop.
problem 2 : getting to 'printf("\n\n ** RESULTS ** \n\n");' or essentially breaking while loop?
solution : you cannot. you will never get EOF as long as you read from keyboard.
workaround : close stdin or use a escape character other than EOF.
EDIT : workaround2 :
->use getchar() itself. but to print those entered char u need to press Enter key. now on windows ctrl+z gives EOF but this should be the **FIRST** input on the line after you press Enter key. well this is not a good solution.
if you want a "Press key display times pressed scenario. there is just no simple way(AFAIK)"
I believe that the first printf statement gets executed, but due to buffering is not displayed on the screen immediately. Use fflush(stdout) to send the contents of the buffer to the screen. Ie:
printf("\n Start pressing some keys!\n\n");
fflush(stdout);

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