Intel XENIX 286 Programmers Guide (86) - Tenox.tc

lint: C Program Checker XENIX Programming
If the variable is used in the same statement in which it is assigned for the first time,
lint determines the order of evaluation of the statement and displays an appropriate
message. For example, in the program fragment
int i, total;
scanf("%d", &i);
total = total + i;
lint warns that the variable "total" is used before it is set since it appears on the right
side of the same statement that assigns its first value.
Static and external variables are always initialized to zero before program execution
begins, so lint does not report such variables if they are used before being set to a value.
Checking for Unreachable Statements
The lint ·program checks for unreachable statements, that is, for unlabeled statements
that immediately follow a goto, break, continue, or return statement. During execution
of a program, the unreachable statements never receive execution control and are
therefore considered wasteful. For example, in the program fragment
int x,y;
return (x + y);
exit (1);
the function call exit after the return statement is unreachable.
Unreachable statements are common when developing programs containing large switch
statements or loops containing break and continue statements. Such statements are
wasteful and should be removed.
During normal operation, lint reports all unreachable break statements. Unreachable
break statements are relatively common (some programs created by the yacc and lex
programs contain hundreds), so it may be desirable to suppress these reports. You can
direct lint to suppress the reports by using the -b option.
Note that lint assumes that all functions eventually return control, so it does not report
as unreachable any statement that follows a function that takes control and never
returns it. For example:
exit (1 );
return;
The call to exit causes the return statement to become an unreachable statement, but
lint does not report it as such.
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