This question already has answers here:
How to overwrite stdout in C
(8 answers)
Closed 4 years ago.
I know how to print string or chars in C, but i'm wondering how i could modify a string that have already been printed in the screen (like when you install some packages and # fills the |####---->| 50%), without using any other functions than syscalls.
You can use the carriage return:
#include <stdio.h>
#include <unistd.h>
int main()
{
printf("%s", "Hello, ");
fflush(stdout);
sleep(1);
printf("\r%s\n", "World!");
return 0;
}
Related
This question already has answers here:
C/C++ printf() before scanf() issue
(2 answers)
Why does printf not flush after the call unless a newline is in the format string?
(10 answers)
Closed 6 months ago.
I'm using Eclipse IDE
I have the following simple code in C language:
#include <stdio.h>
#include <stdlib.h>
int main(void) {
int a;
printf("Enter a number");
scanf("%d",&a);
printf("You have entered %d",a);
return EXIT_SUCCESS;
}
So as you can see, there are two printf's.
but if i run the code on console My scanf is running before my first printf displays.
And all output printed together after the execution of scanf.
Then the result will be like this (This is what I'm getting in my console):
6
Enter a numberYou have entered 6
What i really wanted is:
Enter a number
6
You have entered 6
I tried adding fflush(stdout) but the broblem still exists.
is there any working solution to fix this?
This question already has answers here:
C/C++ printf() before scanf() issue
(2 answers)
Closed 7 months ago.
I was doing c program in eclipse, first printf function is not showing in console, after I entered 2 values it is showing 2 printf out in same line, how to clear this problem
#include <stdio.h>
#include <stdlib.h>
int main(void) {
int a,b,c;
printf("enter two numbers");
scanf("%d%d",&a,&b);
c=a+b;
printf("total is %d",c);
return EXIT_SUCCESS;
}
This is my code
the problem seems to be that the print isn't flushed to the terminal.
when you use printf you actually are writing to a buffer that will be flushed to the terminal after one of the following:
the buffer is full
enough time has passed
you ended your print with '\n'
you give a flush command
I recommend just finishing your print with the '\n'
printf("enter two numbers\n");
This question already has answers here:
Return value of printf() function in C
(13 answers)
How do I explain the output of this simple C code?
(4 answers)
Explain the return value of printf [duplicate]
(3 answers)
Closed 1 year ago.
When I run this code without \n the output is hello5 but with \n the output is hello6, can someone explain?
#include <stdio.h>
//Compiler version gcc 6.3.0
int main()
{
int c;
c = printf("hello\n");
printf("%d",c);
return 0;
}
The printf function returns the total number of characters printed.
When you print "hello\n", that's 6 characters, so c is 6. When you print "hello", that's 5 characters, so c is 5.
This question already has answers here:
What are the rules of automatic stdout buffer flushing in C?
(5 answers)
printf flush at program exit
(4 answers)
Closed 3 years ago.
Until now, I used fflush(stdout) when using printf without \n, since we have to flush the buffer.
But I found that the below code also works fine.
#include <stdio.h>
int main(void){
printf("hello world");
// without fflush(stdout)
}
// output: "hello world"
Is the outcome differs with the compiler? or am I misunderstand something?
This question already has answers here:
printf anomaly after "fork()"
(3 answers)
fork() in c using printf [duplicate]
(2 answers)
Closed 8 years ago.
#include <stdio.h>
#include <unistd.h>
int main(void)
{
int i;
for (i = 0; i < 2; i++) {
fork();
printf("-");
}
return 0;
}
The result of this program is 8"-" : "--------". But if I change 'printf("-");' into 'printf("-\n");', the result of this program will become 6"-": "-\n-\n-\n-\n-\n-\n". Can anyone tell me why?
printf writes to stdout stream which is line buffered. Buffer is a block of memory which belongs to a stream and is used to hold stream data temporarily. This is done to increase efficiency, as file and console I/O is slow in comparison to memory operations. Line buffered means that characters are saved up in the buffer only till a newline is output.