How can I make a C program of a variable in subtraction with an integer and take it's power

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Start by thinking about what you have to do: read in three values: x, a, and n. Then subtract a from x and store the result in x. Create a power value, and set it to 1. Then add a loop - as I told you you would need three hours ago - to iterate between 1 and n. Each time round the loop, multiply power by x and print it. Simple!

If you are having problems getting started at all, then this may help: How to Write Code to Solve a Problem, A Beginner's Guide[^]

Why is x a char data type ?

If you want to calculate this concretely, you need three variables for the calculation.

The question here would be if all three are read in, or where else do they come from ?

If you don't read in X, you could only output the formula without a concrete result. If you have all three values you can calculate the result. The output of the power seems to be calculated and output step by step. For this you need a loop that runs from 1 ... n.

The result for a power would be calculated stepwise like this:

result = (X - a) * (X - a) * (X - a) ...

Since with (x - a) always the same comes out one needs to calculate it only once with u = x - a. This results in

result = (u) * (u) * (u) ...

At each step, the result of a bracket is calculated and multiplied by the previous result.

int a, x, n;

puts("Solver for (x - a) ^ n");

printf("Enter value of a: ");
scanf("%d", &a);

...

int u = x - a;
int result = 1;

for (int i=1; i <= n; i++) {
...