Question 12.1

What's wrong with this code?

char c;
while((c = getchar()) != EOF) ...


For one thing, the variable to hold getchar's return value must be an int. getchar can return all possible character values, as well as EOF. By passing getchar's return value through a char, either a normal character might be misinterpreted as EOF, or the EOF might be altered (particularly if type char is unsigned) and so never seen.

References: K&R1 Sec. 1.5 p. 14
K&R2 Sec. 1.5.1 p. 16
ANSI Sec. 3.1.2.5, Sec. 4.9.1, Sec. 4.9.7.5
ISO Sec. 6.1.2.5, Sec. 7.9.1, Sec. 7.9.7.5
H&S Sec. 5.1.3 p. 116, Sec. 15.1, Sec. 15.6
CT&P Sec. 5.1 p. 70
PCS Sec. 11 p. 157


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