MISRA C++:2008 Rule 7-1-1

A variable which is not modified shall be const qualified

Description

Rule Definition

A variable which is not modified shall be const qualified.

Rationale

Declaring a variable const reduces the chances that you modify the variable by accident.

Polyspace Implementation

The checker flags function parameters or local variables that are not const-qualified but never modified in the function body. Function parameters of integer, float, enum and boolean types are not flagged.

If a variable is passed to another function by reference or pointers, the checker assumes that the variable can be modified. These variables are not flagged.

Troubleshooting

If you expect a rule violation but do not see it, refer to Coding Standard Violations Not Displayed.

Examples

Unmodified Local Variable

#include <string.h>

char returnNthCharacter (int n) {
    char* pwd = "aXeWdf10fg" ; //Noncompliant
    char nthCharacter;
        
    for(int i=0; i < strlen(pwd); i++) {
        if(i==n)
            nthCharacter = pwd[i];
    }
    return nthCharacter;
}

In this example, the pointer pwd is not const-qualified. However, beyond initialization with a constant, it is not reassigned anywhere in the returnNthCharacter function.

Check Information

Group: Declarations

Category: Required