A control structure defines the execution order of the given program statements. There are three types of control structures. Sequence (Linear) Selection Repetition (Iteration) Selection Structure In C language we can use the If and Switch statements to represent the selection structure. If statement also come in two ways. 1. if(condition){ statement; } else{ statement; } 2. if(condition){ statement; } else if{ statement; } else{ statement; } This second way is called as nested if statement. and also there can be only a if condition in a program. ex: 1. #include <stdio.h> #include <stdlib.h> int main() { int no1,no2; printf("enter two numbers"); scanf("%d %d",&no1,&no2); if(no1>no2){ printf("highest is %d \n",no1); } else{ printf("highest is %d \n",no2