C/C++ printf() before scanf() issue

Question

I'm using Eclipse to code in C/C++ and I'm struggling with what might be something pretty easy. In my code below I use printf() and after scanf(). Althougth printf is written before scanf() the output differs. I was able to find out something about similar issue here. But I wasn't able to solve it. Any ideas?

Code:

#include <stdio.h>  int main() {     int myvariable;      printf("Enter a number:");     scanf("%d", &myvariable);     printf("%d", myvariable);      return 0; } 

Expected output:

Enter a number:1 1 

Instead I get:

1 Enter a number:1 

Answer 1

Your output is being buffered. You have 4 options:

1. explicit flush

   fflush after each write to profit from the buffer and still enforce the desiredbehavior/display explicitly.

    fflush( stdout ); 

2. have the buffer only buffer lines-wise

   useful for when you know that it is enough to print only complete lines

    setlinebuf(stdout); 

3. disable the buffer

    setbuf(stdout, NULL); 

4. disable buffering in your console through what ever options menu it provides

---

Examples:

Here is your code with option 1:

#include <stdio.h> int main() {      int myvariable;          printf("Enter a number:");     fflush( stdout );     scanf("%d", &myvariable);     printf("%d", myvariable);     fflush( stdout );      return 0; } 

---

Here is 2:

#include <stdio.h> int main() {      int myvariable;      setlinebuf(stdout);          printf("Enter a number:");     scanf("%d", &myvariable);     printf("%d", myvariable);      return 0; } 

---

and 3:

#include <stdio.h> int main() {      int myvariable;      setbuf(stdout, NULL);           printf("Enter a number:");     scanf("%d", &myvariable);     printf("%d", myvariable);      return 0; } 

Answer 2

Ok, so finally I used something similar to what @zsawyer wrote as an option labelled 3. In my code I inserted this line:

setvbuf(stdout, NULL, _IONBF, 0); 

As a first line in main():

#include <stdio.h>  int main() {     setvbuf(stdout, NULL, _IONBF, 0);      int myvariable;      printf("Enter a number:");     scanf("%d", &myvariable);     printf("%d", myvariable);      return 0; } 

I got it from here.