I have a question regarding this metric.

For example, if I have the following code, how many path does the function main have?

void main()
{
    int i = 0, j = 0, k = 0;
    for (i=0; i<10; i  )
    {
        for (j=0; j<10; j  )
        {
            for (k=0; k<10; k  )
            {
                if (i < 2 )
                    printf("value is more than 2\n");
                if (i > 5)
                    printf("value is less than 5\n");
            }
        }
    }
}

The first three for loops should have 3 paths and one additional that bypasses all control flow statements, then what about the nested if statement? Is it 1x1 = 1 path?

Anyone without matlab account, the following description is on the website:

A control flow statement introduces branches and adds to the original one path.

    if-else if-else: Each if keyword introduces a new branch. The contribution from an if-else if-else block is the number of branches plus one (the original path). If a catch-all else is present, all paths go through the block; otherwise, one path bypasses the block.

    For instance, a function with an if(..) {} else if(..) {} else {} statement has three paths. A function with one if() {} only has two paths, one that goes through the if block and one that bypasses the block.

for and while: Each loop statement introduces a new branch. The contribution from a loop is two - a path that goes through the loop and a path that bypasses the loop.
If more than one control flow statement are present in a sequence without any nesting, the number of paths is the product of the contributions from each control flow statement.

For instance, if a function has three for loops and two if-else blocks, one after another, the number of paths is 2 × 2 × 2 × 2 × 2 = 32.

void func()
{
    int i = 0, j = 0, k = 0;
    for (i=0; i<10; i  )
    {
        for (j=0; j<10; j  )
        {
            for (k=0; k<10; k  )
            {
                if (i < 2 )
                    ;
                else
                {
                    if (i > 5)
                        ;
                    else
                        ;
                }
            }
        }
    }
}

In this example, func has six paths: three from the for statements, two from the if statements plus the original path that bypasses all control flow statements.

CodePudding user response：

According to the description:

If more than one control flow statement are present in a sequence without any nesting, the number of paths is the product of the contributions from each control flow statement.

and

The contribution from an if-else block is the number of branches plus one (the original path)

your two if statements contribute 2 paths each, so that's 2 x 2 = 4 paths, and then each of your loop contributes one additional path, so the total would be 7 paths.

However, this description does not make much sense to me, since this code has only one possible path:

if (true) {
    // this part is always executed
}

This can seem obvious, but more complicated situations can easily reduce the number of possible paths, just like in your example where there are only three possibilities: either i < 2 or i > 5 or i >= 2 && i <= 5.

I suppose the metric's description would make sense as an upper bound on the number of paths.