Output Window Closes After Pressing Enter

[Nobody/Anonymous]

I have searched the forum, read the faq, and can't find this anywhere.

I can keep the output window open when I hardwire the values in and then use getchar (), but when I use scanf to interactively input the values then hit enter the window closes. If I've missed this somewhere can someone please post a link

I am using devcpp-4.9.9.2

This is my program:

include <stdio.h>

main()

{

int a, b;

b = a + a;

printf("Input the value for a: \n");
scanf("%lf", &a);

getchar ();

return 0;

}

This is my compile log:

Compiler: Default compiler
Executing g++.exe...
g++.exe "C:\Documents and Settings\Owner\Desktop\Untitled.cpp" -o "C:\Documents and Settings\Owner\Desktop\Untitled.exe" -I"C:\Dev-Cpp\lib\gcc\mingw32\3.4.2\include" -I"C:\Dev-Cpp\include\c++\3.4.2\backward" -I"C:\Dev-Cpp\include\c++\3.4.2\mingw32" -I"C:\Dev-Cpp\include\c++\3.4.2" -I"C:\Dev-Cpp\include" -L"C:\Dev-Cpp\lib"
Execution terminated
Compilation successful

[Nobody/Anonymous]

there are still characters in the que. in this case call fflush with stdin before the getchar and it should work.

snork

[Nobody/Anonymous]

I'm sorry, I'm not quite sure what you mean when you say,

"call fflush with stdin before the getchar"

Can you show me an example with this added to my program?

Is stdin a preprocessor instruction?

   #include <stdin>

[Nobody/Anonymous]

fflush(stdin)

snork

[Josh]

I can input the value for a, but no matter what value I put in for a, b is always equal to 0.

Am I missing something?

This is my program:

include <stdio.h>

main()

{

int a, b;

/ When I put the value in like this b = 2 /
a = 1;

/* When I put the value in using scanf b = 0.

printf("Input the value for a: \n");
scanf("%lf", &a);

I've double checked and I'm pretty sure I've typed everything in correctly.

*/

b = a + a;

printf("b = %d, \n", b);

fflush(stdin);

getchar ();

return 0;

}

Compile Log:

Compiler: Default compiler
Executing g++.exe...
g++.exe "C:\Documents and Settings\Owner\Desktop\Untitled4.cpp" -o "C:\Documents and Settings\Owner\Desktop\Untitled4.exe" -I"C:\Dev-Cpp\lib\gcc\mingw32\3.4.2\include" -I"C:\Dev-Cpp\include\c++\3.4.2\backward" -I"C:\Dev-Cpp\include\c++\3.4.2\mingw32" -I"C:\Dev-Cpp\include\c++\3.4.2" -I"C:\Dev-Cpp\include" -L"C:\Dev-Cpp\lib"
Execution terminated
Compilation successful

Output:

Input the value for a:
1
b = 0,

[Josh]

"there are still characters in the que. in this case call fflush with stdin before the getchar and it should work."

Can some tell me what this means? Am I always going to have to use fflush(stdin); with scanf, or is there some other way to get the characters out of the que?

[Nobody/Anonymous]

scanf("%lf", &a); // %i or %d are acceptable for integers

[Josh]

Thanks for all the help. I had thought maybe I should use something other than %lf because the values were integers, but for some reason I thought my professor said %lf was all you could use in scanf. Must of heard him wrong.