Detecting EOF in C

c stdio
itsaboutcode picture itsaboutcode · Sep 15, 2009 · Viewed 120.1k times · Source

I am using the following C code to take input from user until EOF occurs, but problem is this code is not working, it terminates after taking first input. Can anyone tell me whats wrong with this code. Thanks in advance.

float input;

printf("Input No: ");
scanf("%f", &input);

while(!EOF)
{
    printf("Output: %f", input);
    printf("Input No: ");
    scanf("%f", &input);
}

Answer

CB Bailey picture CB Bailey · Sep 15, 2009

EOF is just a macro with a value (usually -1). You have to test something against EOF, such as the result of a getchar() call.

One way to test for the end of a stream is with the feof function.

if (feof(stdin))

Note, that the 'end of stream' state will only be set after a failed read.

In your example you should probably check the return value of scanf and if this indicates that no fields were read, then check for end-of-file.

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