Warning with struct initialization

Question

I have this struct:

struct ChangeIntItem
{
    char *unit;
    const char **parser;
    int *changevalue;
    uint16_t *change_eeprom_value;
    int maximum;
    int minimum;
};

I want to initialize other variables with this struct-Variable:

struct ChangeIntItem ChangeIntItemTypeBoolean = { .unit = "", .minimum = 0, .maximum = 1, .parser = {"off", "on"}};

It is working fine but I get some warnings:

Severity    Code    Description Project File    Line
Warning     braces around scalar initializer    Handsteuerung   C:\Users\...    11

Severity    Code    Description Project File    Line
Warning     (near initialization for 'ChangeIntItemTypeBoolean.parser') Handsteuerung   C:\Users\...    11

Severity    Code    Description Project File    Line
Warning     initialization from incompatible pointer type   Handsteuerung   C:\Users\...    11

Severity    Code    Description Project File    Line
Warning     (near initialization for 'ChangeIntItemTypeBoolean.parser') Handsteuerung   C:\Users\...    11

Severity    Code    Description Project File    Line
Warning     excess elements in scalar initializer   Handsteuerung   C:\Users\...    11

Severity    Code    Description Project File    Line
Warning     (near initialization for 'ChangeIntItemTypeBoolean.parser') Handsteuerung   C:\Users\...    11

In another case I wrote a function which sets the variables of the struct to default-values but I prefer this method because its much shorter.

All mistakes where caused by '.parser = {"off", "on"}' but I don't get my mistake...

LPs · Accepted Answer · 2016-07-06 10:28:18Z

5

You can use compound literals, so change init to

struct ChangeIntItem ChangeIntItemTypeBoolean = { .unit = "", .minimum = 0, .maximum = 1, .parser = (const char *[]){"off", "on"}};

Test

#include <stdio.h>
#include <stdint.h>

struct ChangeIntItem
{
    char *unit;
    const char **parser;
    int *changevalue;
    uint16_t *change_eeprom_value;
    int maximum;
    int minimum;
};

int main()
{
    struct ChangeIntItem ChangeIntItemTypeBoolean = { .unit = "", .minimum = 0, .maximum = 1, .parser = (const char *[]){"off", "on"}};

    printf ("%s - %s\n", ChangeIntItemTypeBoolean.parser[0], ChangeIntItemTypeBoolean.parser[1]);
}

Output

off - on

answered Jul 6, 2016 at 10:28

LPs

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3 Comments

Lundin Over a year ago

Alternatively, parser could be a flexible array member of type const char* parser[]. There are very few cases where pointer-to-pointer variable declarations make sense.

LPs Over a year ago

@Lundin Yes, with VLA parser should be last member of struct, shouldn't it?

GURKE Over a year ago

Thank you! Sometimes its easier than you think ;)

2501 · Accepted Answer · 2016-07-06 10:28:46Z

4

Member parser is a pointer.

Change it to an array of pointers, so the initialization can be kept the same:

 const char *parser[2];

Or use a compound literal or another variable:

.parser = ( const char*[]){"off", "on"}

const char* array[2] = {"off", "on"};
.parser = array

answered Jul 6, 2016 at 10:28

2501

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1 Comment

2501 Over a year ago

@LPs No, it is a pointer. Phrase pointer of pointers doesn't have any meaning.

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