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Top Forums Programming Why does fflush(stdin) fail to work ? Post 303022565 by Azrael on Monday 3rd of September 2018 12:45:52 AM
Old 09-03-2018
When an invalid character is entered the code goes into an endless loop. It seems this line:
Code:
while (scanf("%lf", &number) != 1)

Is essentially the same as this:
Code:
while(1)

It may check the condition, but in this case that condition will never change. You could that same check in an if statement so it is only checked once. Or use the while(1) in that loop with breaks to jump out of the loop when needed. You might want to look into fgets. The scanf function is great for learning, but can introduce potential security problems. Hope that helps.
 

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gets(3C)						   Standard C Library Functions 						  gets(3C)

NAME
gets, fgets - get a string from a stream SYNOPSIS
#include <stdio.h> char *gets(char *s); char *fgets(char *s, int n, FILE *stream); DESCRIPTION
The gets() function reads bytes from the standard input stream (see intro(3)), stdin, into the array pointed to by s, until a newline char- acter is read or an end-of-file condition is encountered. The newline character is discarded and the string is terminated with a null byte. If the length of an input line exceeds the size of s, indeterminate behavior may result. For this reason, it is strongly recommended that gets() be avoided in favor of fgets(). The fgets() function reads bytes from the stream into the array pointed to by s, until n-1 bytes are read, or a newline character is read and transferred to s, or an end-of-file condition is encountered. The string is then terminated with a null byte. The fgets() and gets() functions may mark the st_atime field of the file associated with stream for update. The st_atime field will be marked for update by the first successful execution of fgetc(3C), fgets(), fread(3C), fscanf(3C), getc(3C), getchar(3C), gets(), or scanf(3C) using stream that returns data not supplied by a prior call to ungetc(3C) or ungetwc(3C). RETURN VALUES
If end-of-file is encountered and no bytes have been read, no bytes are transferred to s and a null pointer is returned. For standard-con- forming (see standards(5)) applications, if the end-of-file indicator for the stream is set, no bytes are transferred to s and a null pointer is returned whether or not the stream is at end-of-file. If a read error occurs, such as trying to use these functions on a file that has not been opened for reading, a null pointer is returned and the error indicator for the stream is set. If end-of-file is encoun- tered, the EOF indicator for the stream is set. Otherwise s is returned. ERRORS
Refer to fgetc(3C). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
lseek(2), read(2), ferror(3C), fgetc(3C), fgetwc(3C), fopen(3C), fread(3C), getchar(3C), scanf(3C), stdio(3C), ungetc(3C), ungetwc(3C), attributes(5), standards(5) SunOS 5.10 15 Oct 2003 gets(3C)
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