CODEWITHSUNDEEP
cloopsfor-loopforeach
rango
rango

Reputation: 311

Implementing loops on the basis of condition in C

I have a set of statements that need to be executed in two different loops; the loops identified on the result of a check condition. There are multiple such sets of this type.

Set A : statement 1
        statement 2
        statement 3

Set B : statement 4
        statement 5
        statement 6

and so on..

Now they need to be executed as follows:

if(condition 1)
    loop over some Loop A
        execute Set A
else if(condition 2)
    loop over some loop B
        execute Set A

These loops can be completely different from each other.

Now, for the sake of code clarity, I don't wish to write the code as mentioned above. Another reason being I'll have to make multiple sets in order to group them together.

Is there any mechanism by which I could achieve the following:

CHECK_CONDITION_AND_LOOP_HERE
    execute Set A

I've tried using macros to achieve this, using braced-group within expression but could not . I also tried using ternary operators as well as fall through a switch case to achieve this, but could not get the same result.

Is there any way in C using which I could achieve the desired behavior?

Sample code for the problem:

if(condition A)
    for(i=0; i<10; i++, k*=2) {
        execute Set A;  //Operations performed here use variable k
    }
else if(condition B)
    for(j=5; j<75; j+=5, k*=arr[j]) {
        execute Set A;  //Operations performed here use variable k
    }

Upvotes: 1

Views: 67

Answers (2)

user3386109
user3386109

Reputation: 34829

The answer to Version 1 of the question:

Given that the only difference is the range of values over which the statements are executed, you can use a couple of variables to store the range end-points, e.g.

int first = 0;
int last = -1;

if (condition1) {
    first = 1;
    last = 10;
} else if (condition2) {
    first = 3;
    last  = 7;
}

for ( int i = first; i <= last; i++ )
    execute set A

Note that initializing last to be less than first prevents the body of the loop from running if neither condition is met.

The answer to Version 2 of the question:

Here's the code from the question. I've made some changes for clarity, and to make the question more concrete.

if (cond1)
    for (initA;condA;updateA)
        execute SetX
else if (cond2)
    for (initB;condB;updateB)
        execute SetX

Here's the refactored code

int is1 = cond1;
int is2 = is1 ? 0 : cond2;

if (is1)
    initA;
if (is2)
    initB;

while ( (is1 && condA) || (is2 && condB) )
{
    execute SetX
    if ( is1 )
        updateA;
    if ( is2 )
        updateB;
}

Upvotes: 4

Roney Michael
Roney Michael

Reputation: 3994

A function, maybe?

void func_A() {
    printf("Here0\n");
    printf("Here1\n");
}

...

if(a < b) {
    for(i = 1; i <= 10; i++) {
        func_A()
    }
}
else if(a == b) {
    for(i = 3; i <= 7; i++) {
        func_A()
    }
}

Or if you want to only make one call/block:

if(a < b) {
    min = 1; max = 10;
}
else if(a == b) {
    min = 3; max = 7;
}
for(i = 3; i <= 7; i++) {
    printf("Here0\n");
    printf("Here1\n");
}

Upvotes: 1

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