Failing to pass variable of struct-array as function parameter

Question

I am fairly new to the concept of structs in C, and have run into a problem. I have looked for any similar problems posted here, but cannot find any. What I am trying to do is pass a variable in an array of structs as a parameter in a function, as so:

struct Student
{
    float average;
    int ID;
    int grades[5];
    char firstName[20], lastName[20];
};

void main(void)
{
    struct Student sTable[10];

    float maxAverage(float sTable[].average)
    {
        int i;
        float max = 0;

        for(i = 0;i < 10; ++i)
        {
            if(sTable[i].value > max)
            {
                max += sTable[i].value;
            }
        }
        return max;
    }

    printf("%f",maxAverage(sTable[].average));
}

David Heffernan · Accepted Answer · 2011-10-20 14:55:09Z

2

There are a few problems here.

You cannot nest functions inside other functions like you can in languages like Java, C#, Python.
You are passing the struct array incorrectly.
Your main declaration is incorrect.

You want code something like this:

struct Student
{
    float average;
    int ID;
    int grades[5];
    char firstName[20], lastName[20];
};

float maxAverage(struct Student sTable[])
{
    int i;
    float max = 0;

    for(i = 0;i < 10; ++i)
    {
        if(sTable[i].value > max)
        {
            max += sTable[i].average;
        }
    }
    return max;
}

int main(void)
{
    struct Student sTable[10];
    //initialize sTable
    printf("%f", maxAverage(sTable));
    return 0;
}

Note that you are missing initialization of sTable.

What's more you really ought to pass the length of the array as a parameter to maxAverage. That will then allow you more flexibility to use arrays of any length.

answered Oct 20, 2011 at 14:55

David Heffernan

616k46 gold badges1.1k silver badges1.5k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

jwodder Over a year ago

The references to .value in maxAverage should be .average, I believe.

David Heffernan Over a year ago

@jwodder Thanks, I just moved the code around in the editor, didn't try to compile it.

jwodder · Accepted Answer · 2011-10-20 14:54:19Z

0

First of all, you can't declare or define a function inside another function, so move maxAverage outside of main (which, incidentally, should return int, not void). Secondly, given an array of structs, you can't just automatically create an array of the values from a certain field of the structs; if you want to, you would have to manually declare a separate array of (in this case) floats and then copy over the average fields one by one. A simpler way would be to simply pass sTable itself to maxAverage and have maxAverage only operate on the average fields of the structs in the array.

answered Oct 20, 2011 at 14:54

jwodder

58.1k12 gold badges116 silver badges134 bronze badges

Collectives™ on Stack Overflow

Failing to pass variable of struct-array as function parameter

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related