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Code Block
bgColor#FFcccc
#define EOF -1
/* // ... */
if (c EOF) {
   /* // ... */
}

Wiki Markup
In this example, the programmer has mistakenly omitted the comparison operator (see \[[MSC02-A. Avoid errors of omission]\]) from the conditional statement, which should be {{c \!= EOF}}. After macro expansion, the conditional expression is incorrectly evaluated as a binary operation: {{c-1}}. This is syntactically correct, even though it is certainly not what the programmer intended.

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Code Block
bgColor#ccccff
#define EOF (-1)
/* // ... */
if (c != EOF) {
   /* // ... */
}

Risk Assessment

Failure to use parenthesis around macro definitions that contain operators can result in unintended program behavior.

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