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The following table summarizes C-compliant conversion specifiers along with the flag characters valid for each specification (the apostrophe ('), -, +, the space character, and # in columns 2 through 5) and length modifiers (h, hh, l, ll, j, z, t, and L in columns 6 through 13) and the type of the expected argument. Valid and meaningful combinations of a conversion specification, flag character, and length modifier is denoted by the (tick) symbol in the corresponding cell or by the name of the type argument affected by the length modifier. Valid combinations that have no effect are denoted by N/E. Using a combination of a conversion specification, flag character, and length modifier denoted by the (error) symbol or a specification not listed in the table, or using an argument of an unexpected type, may result in undefined behavior. See undefined behaviors 153, 157, 158, 161, and 162 in Annex J of C11.

Conversion
Specifier
Character

' XSI

-
+
SPACE


#


0

 


h


hh


l


ll


j


z


t


L

Argument
Type

d, i

(tick)

(tick)

(error)

(tick)

 

short

char

long

long long

intmax_t

size_t

ptrdiff_t

(error)

signed integer

o

(error)

(tick)

(tick)

(tick)

 

short

char

long

long long

intmax_t

size_t

ptrdiff_t

(error)

unsigned integer

u

(tick)

(tick)

(error)

(tick)

 

short

char

long

long long

intmax_t

size_t

ptrdiff_t

(error)

unsigned integer

x

(error)

(tick)

(tick)

(tick)

 

short

char

long

long long

intmax_t

size_t

ptrdiff_t

(error)

unsigned integer

X

(error)

(tick)

(tick)

(tick)

 

short

char

long

long long

intmax_t

size_t

ptrdiff_t

(error)

unsigned integer

f, F

(tick)

(tick)

(tick)

(tick)

 

(error)

(error)

N/E

N/E

(error)

(error)

(error)

long double

double or long double

e, E

(error)

(tick)

(tick)

(tick)

 

(error)

(error)

N/E

N/E

(error)

(error)

(error)

long double

double or long double

g, G

(tick)

(tick)

(tick)

(tick)

 

(error)

(error)

N/E

N/E

(error)

(error)

(error)

long double

double or long double

a, A

(tick)

(tick)

(tick)

(tick)

 

(error)

(error)

N/E

N/E

(error)

(error)

(error)

long double

double or long double

c

(error)

(tick)

(error)

(error)

 

(error)

(error)

wint_t

(error)

(error)

(error)

(error)

(error)

int or wint_t

s

(error)

(tick)

(error)

(error)

 

(error)

(error)

NTWS

(error)

(error)

(error)

(error)

(error)

NTBS or NTWS

p

(error)

(tick)

(error)

(error)

 

(error)

(error)

(error)

(error)

(error)

(error)

(error)

(error)

void*

n

(error)

(tick)

(error)

(error)

 

short*

char*

long*

long long*

intmax_t*

size_t*

ptrdiff_t*

(error)

pointer to integer

C XSI

(error)

(tick)

(error)

(error)

 

(error)

(error)

(error)

(error)

(error)

(error)

(error)

(error)

wint_t

S XSI

(error)

(tick)

(error)

(error)

 

(error)

(error)

(error)

(error)

(error)

(error)

(error)

(error)

NTWS

%

(error)

(tick)

(error)

(error)

 

(error)

(error)

(error)

(error)

(error)

(error)

(error)

(error)

none

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  • SPACE—the space (' ') character
  • N/E—No effect
  • NTBS—char* argument pointing to a null-terminated byte string
  • NTWS—wchar_t* argument pointing to a null-terminated wide-character string
  • XSI—ISO/IEC 9945-2003 XSI extension

Noncompliant Code Example

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Tool

Version

Checker

Description

LDRA tool suite

Include Page
LDRA_V
LDRA_V

486 S
589 S

Fully implemented.

GCC

Include Page
GCC_V
GCC_V

 

Can detect violations of this recommendation when the -Wformat flag is used.

Klocwork

Include Page
Klocwork_V
Klocwork_V

SV.FMT_STR.

 

PRQA QA-C
Include Page
PRQA_V
PRQA_V
 

0179 (U)
0180 (C99)
0184 (U)
0185 (U)
0190 (U)
0191 (U)
0192 (U)
0193 (U)
0194 (U).
0195 (U).
0196 (U)
0197 (U)
0198 (U)
0199 (U)
0200 (U).
0201 (U)
0202 (I)
0206 (U)

Partially implemented

Related Vulnerabilities

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