#pragma warn directive in c

In c there are many warning messages which can be on or off with help of #pragma warn.

Syntax :

#pragma warn +xxx

#pragma warn –xxx

#pragma warn .xxx

Where

+ means on

- means off

. means on/off (toggle)

xxx is indicate particular warning code in thee alphabet. Example :

rvl is warning code which means function should return a value.

#include<stdio.h>

#pragma warn –rvl

int main(){

    printf("It will not show any warning message");

    return 0;

}

Output: It will not show any warning message

When you will execute the above program then compiler will not show the warning message function should return a value because rvl warning is off.

List of warning code :

S.N.	Warning message	Code
ANSI Violations
1	Assigning 'type' to 'enumeration'	eas
2	Bit fields must be signed or unsigned int	bbf
3	Both return and return with a value used	ret
4	Declare type 'type' prior to use in prototype	dpu
5	Division by zero	zdi
6	Hexadecimal value contains more than 3 digits	big
7	Initializing 'enumeration' with 'type'	bei
8	'identifier' is declared as both external and static	ext
9	Ill-formed pragma	ill
10	Initialization is only partially bracketed	pin
11	Redefinition of 'macro' is not identical	dup
12	Suspicious pointer conversion	sus
13	Undefined structure 'structure'	stu
14	Void functions may not return a value	voi
Frequent Errors
1	Code has no effect	eff
2	Function should return a value	rvl
3	Parameter 'parameter' is never used	par
4	Possible use of 'identifier' before definition	def
5	Possibly incorrect assignment	pia
6	Unreachable code	rch
Less Frequent Errors
1	Ambiguous operators need parentheses	amb
2	Array variable 'identifier' is near	ias
3	Call to function with no prototype	pro
4	Call to function 'function' with no prototype	pro
5	Condition is always false	wccc
6	Condition is always true	wccc
7	'identifier' declared but never used	use
8	'identifier' is assigned a value that is never used	aus
9	No declaration for function 'function'	nod
10	Structure passed by value	stv
11	Superfluous & with function	amp
Portability Warnings
1	Constant is long	cln
2	Constant out of range in comparison	rng
3	Conversion may lose significant digits	sig
4	Non portable pointer comparison	cpt
5	Non portable pointer conversion	rpt
6	Mixing pointers to signed and unsigned char	ucp

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