#include<iostream.h>
#include<string.h>
typedef char Text[80];
void main()
{
    Text T="Indian";
    int Count=strlen(T);
    cout<<T<<"has"<<Count<<"characters"<<endl;
}

The function prototype serves to ensure that calls to the function are made with the proper number and types of arguments.In the case of function overloading the different prototypes serve to distinguish which version of the function to call.
The compiler will complain with an error if no function prototype is found for any particular call to a function.
e.g.Program to illustrate use of function prototyping.
#include<iostream.h>
int square(int);          //Function prototype
int main()
{
 for(int x=1;x<=10;x++)
     cout<<square(x)<<"  ";
   cout<<endl;
return 0;
}                           //Function definition
int square(int y)
{
   return(y*y);
}

Differences between actual and formal parameters are as follows:

e.g. Program to swap the value of two numbers to show actual and formal parameters.
#include
#include
void swap( int n1,int2)   //Formal Parameters
{
  int temp=n1;
  n1=n2;
  cout<<"Values of num1 and num2 after swapping:";
  cout< }
void main()
{
   int num1,num2;
   clrscr();
   cout<<"Enter two numbers: ";
   cin>>num1>>num2;
   swap(num1,num2);    //Actual parameters
   getch();
}

m=0.1
k=0
j=0

In this loop, there are not brackets surrounding the code block of the while loop. Therefore, only the line immediately following the while statement repeats. Since, that line does not modify counter, its value will always be 1. Hence, it's from infinite loop. To fix, we need to add grouping brackets around the lines after the while loop, i.e.
while(c<100)
{
     cout<<c<<"\n";
     c++;
}

Line 1=5&8
Line 2=11&9
Line 1=6&9
Line 1=12&10

The operators are hierarchically arranged according to their precedence or we can say according to the order of evaluation. Assignment operators like =, +=, -=, #=, /=, etc., have a lower precedence than any of the other operators. Therefore, unary operations, arithmetic operations, relational operations, equality operations and logical operations are all carried out before assignment operations.

Associativity means the order in which consecutive operators within the same precedence group are carried out. The assignment operations have a right to left associativity, which means that the compiler starts on the right of the expression and works towards.

(i) # is missing,

(ii) main should be in the lower case, followed by semicolon.

(iii) float should be in lower case.

(iv) Output operator should be <<.

(v) In place of a>>b, it should be x and y and semicolon is also missing.

(vi) String should be enclosed in double quotes in place of single quotes and two numbers cannot be displayed as a,b, it should be  << in place of comma(,).

typedef keyword is used to assign alternative names to existing data types.
e.g. typedef int in;
Now, whenever we want to declare a variable of types integer, rather than using int, we can use 'in' keyword in place.
e.g. void main()
       {
          typedef int in;
                         //in is an alternetive name to int 
          in a=10;
          cout<<a;  // a is of type integer

The output is 5, 3, 4, 4 

Type casting It is used by the programmer to convert value of one type to another type. It is forced type conversion. It is done by putting the target datatype in parentheses before the data to be converted.
e.g. float X=(double)15/6);

Automatic type conversion It is automatically done by the compiler itself wherever required. It is implicit type conversion
e.g. float X=3;

An unsigned int can represent 0 to 65536 value in total, whereas a signed int can represent -32768 to 32767, i.e. 65536 values. The total numbers represented by both integers are the same but the range represented by unsigned int becomes double because in place of negative numbers positive values are represented thereby increasing the range by 32768 numbers as there are many negative values represented by signed int.

1*1=1
1*3=3
1*5=5
2*1=2
2*3=6
2*5=10
a=32
Now k=2, b=2, c=2.666667

#include
#include
void main()
{
    int n, i;
    clrscr();
    cout<<"Enter the number to find the multiple";
    cin>>n;
    for(i=1;i<=10;i++)
        cout< getch();
}