According to the C Standard, 6.4.5, paragraph 3 [ISO/IEC 9899:20112024]:
A A character string literal is a sequence of zero or more multibyte characters enclosed in double-quotes, as in "xyz". A UTF−8 UTF-8 string literal is the same, except prefixed by u8. A wide wchar_t string literal is the same, except prefixed by the letter
L
,u
, orU
.L. A UTF-16 string literal is the same, except prefixed by u. A UTF-32 string literal is the same, except prefixed by U. Collectively, wchar_t, UTF-16, and UTF-32 string literals are called wide string literals.
At compile time, string literals are used to create an array of static storage duration of sufficient length to contain the character sequence and a terminating null character. String literals are usually referred to by a pointer to (or array of) characters. Ideally, they should be assigned only to pointers to (or arrays of) const char
or const wchar_t
. It is unspecified whether these arrays of string literals are distinct from each other. The behavior is undefined if a program attempts to modify any portion of a string literal. Modifying a string literal frequently results in an access violation because string literals are typically stored in read-only memory. (See undefined behavior 33.)
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Tool | Version | Checker | Description | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Astrée |
| string-literal-modfication write-to-string-literal | Fully checked | ||||||||||||||||||
Axivion Bauhaus Suite |
| CertC-STR30 | Fully implemented | ||||||||||||||||||
Compass/ROSE | Can detect simple violations of this rule | ||||||||||||||||||||
Coverity |
| PW | Deprecates conversion from a string literal to "char *" | ||||||||||||||||||
Helix QAC |
| C0556, C0752, C0753, C0754 C++3063, C++3064, C++3605, C++3606, C++3607 | |||||||||||||||||||
| CERT.STR.ARG.CONST_TO_NONCONST | ||||||||||||||||||||
LDRA tool suite |
| 157 S | Partially implemented | ||||||||||||||||||
Parasoft C/C++test |
| CERT_C-STR30-a | A string literal shall not be modified | ||||||||||||||||||
PC-lint Plus |
| 489, 1776 | Partially supported | ||||||||||||||||||
Polyspace Bug Finder |
| CERT C: Rule STR30-C | Checks for writing to const qualified object (rule fully covered) | PRQA QA-C | |||||||||||||||||
Include Page | PRQA QA-C_v | PRQA QA-C_v | 0556, 0752, 0753, 0754 | Partially implemented | PRQA QA-C++ | Include Page | | cplusplus:PRQA QA-C++_V | 3063, 3064, 3605, 3606, 3607, 3842 | ||||||||||||
PVS-Studio |
| V675 | |||||||||||||||||||
RuleChecker |
| string-literal-modfication | Partially checked | ||||||||||||||||||
Splint |
| ||||||||||||||||||||
TrustInSoft Analyzer |
| mem_access | Exhaustively verified (see one compliant and one non-compliant example). |
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Bibliography
[ISO/IEC 9899:20112024] | 6.4.5, "String Literals" |
[Plum 1991] | Topic 1.26, "Strings—String Literals" |
[Summit 1995] | comp.lang.c FAQ List, Question 1.32 |
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