What file extension is used to name a compressed folder

Cprogram to find //perimeter of rectangle printf(" \n perimeter of rectangle \n"); printf(""); printf("\n enter width and length of the rectangle : "); scanf("%f%f", & width,& length); perimeter = 2 * (width + length); printf("perimeter of rectangle is: %.3f", perimeter);  

The answer is b ^_^ well tbh im guessing idk