Clarified variable names and added some 3 extra equation functions

ARRAY.c

@@ -49,7 +49,7 @@ void deletion(){
 }
 
 void updation(){
-    printf("ENTER THE POSITION WHERE U WANT TO UPDATE");
+    printf("ENTER THE POSITION WHERE YOU WANT TO UPDATE");
     scanf("%d",&position);
     if(position>n){
         printf("\n INVALID POSITION\n");
@@ -72,7 +72,7 @@ void linear_search(){
         }
     }
     if(choice!=20){
-        printf("\nELEMNT NOT FOUND!!!");
+        printf("\nELEMENT NOT FOUND!!!");
     }
     menu();
 }
@@ -197,3 +197,4 @@ int main(){
 
    return 0;
 }
+

Addition.c

@@ -1,8 +1,11 @@
 #include<stdio.h>
-void main()
-{ int a,b,c;
+int main()
+{ int a,b,sum,difference;
 printf("Enter two Numbers : ");
 scanf("%d %d",&a,&b);
-c=a+b;
-printf("The Sum is %d",c);
+sum=a+b;
+difference=a-b;
+printf("The Sum is %d",sum);
+printf("The Difference is %d",difference);
+return 0;
 }

AreaAndCircumference.c

@@ -3,11 +3,12 @@
 #include<stdio.h>
 int main()
 {
-    float r, a ,c;
+    float radius, area ,circumference;
     printf("enter radius :\n");
-    scanf("%f", &r);
-    a = 3.14*r*r;
-    c = 2*3.14*r;
-    printf("Area = %f\n circumference = %f\n",a,c);
+    scanf("%f", &radius);
+    area = 3.14*radius*radius;
+    circumference = 2*3.14*radius;
+    printf("Area = %f\n circumference = %f\n",area,circumference);
     return 0;
 }
+

Area_of_Circle.c

@@ -1,8 +1,13 @@
 #include<stdio.h>
-void main()
-{ float a,r;
+#define PI 3.14
+int main()
+{ float area, r, circumference;
 printf("Enter the Radius : ");
 scanf("%f",&r);
-a=3.14*r*r;
-printf("Area is %f",a);
+area=PI*r*r;
+circumference=2*PI*r;
+printf("Area is %f",area);
+printf("Circumference is %f", circumference);
+return 0;
 }
+

Area_of_Square.c

@@ -1,8 +1,11 @@
 #include<stdio.h>
-void main()
-{ float a,r;
-printf("Enter the Radius : ");
-scanf("%f",&s);
-a=s*s;
-printf("Area is %f",a);
+int main()
+{ float area,side,perimeter;
+printf("Enter the length of side: ");
+scanf("%f",&side);
+area=side*side;
+perimeter=4*side;
+printf("Area is %f",area);
+printf("Perimeter is %f", perimeter);
+return 0;
 }

Area_of_Triangle.c

@@ -1,10 +1,10 @@
 #include<stdio.h>
 void main()
-{ float a,b,h;
+{ float area,base,height;
 printf("Enter the base : ");
-scanf("%f",&b);
+scanf("%f",&base);
 printf("Enter the height : ");
-scanf("%f",&h);
-a=0.5*b*h;
-printf("Area is %f",a);
+scanf("%f",&height);
+area=0.5*base*height;
+printf("Area is %f",area);
 }