C++ Basic Input/Output

C++ Basic Input/Output

Definition

The C++ standard libraries provide an extensive set of input/output capabilities which we will see in subsequent chapters. This chapter will discuss very basic and most common I/O operations required for C++ programming.

C++ I/O occurs in streams, which are sequences of bytes. If bytes flow from a device like a keyboard, a disk drive, or a network connection etc. to main memory, this is called input operation and if bytes flow from main memory to a device like a display screen, a printer, a disk drive, or a network connection, etc., this is called output operation.

I/O Library Header Files

There are following header files important to C++ programs −

Sr.No	Header File & Function and Description
1	<iostream> This file defines the cin, cout, cerr and clog objects, which correspond to the standard input stream, the standard output stream, the un-buffered standard error stream and the buffered standard error stream, respectively.
2	<iomanip> This file declares services useful for performing formatted I/O with so-called parameterized stream manipulators, such as setw and setprecision.
3	<fstream> This file declares services for user-controlled file processing. We will discuss about it in detail in File and Stream related chapter.

The Standard Output Stream (cout)

The predefined object cout is an instance of ostream class. The cout object is said to be "connected to" the standard output device, which usually is the display screen. The cout is used in conjunction with the stream insertion operator,

Input:-

#include <iostream>

using namespace std;

 int main() {

   char name[50];

   cout << "Please enter your name: ";

   cin >> name;

   cout << "Your name is: " << name << endl;

}

 OutPut:-

Please enter your name: M.Asif Saeed

Your name is: M.Asif Saeed

Math Operators Program

Math Operators Program

Input:

#include <cmath>

using namespace std;

int main () {

   // number definition:

   short  s = 10;

   int    i = -1000;

   long   l = 100000;

   float  f = 230.47;

   double d = 200.374;

   // mathematical operations;

   cout << "sin(d) :" << sin(d) << endl;

   cout << "abs(i)  :" << abs(i) << endl;

   cout << "floor(d) :" << floor(d) << endl;

   cout << "sqrt(f) :" << sqrt(f) << endl;

   cout << "pow( d, 2) :" << pow(d, 2) << endl;

   return 0;

}

Output:

Numbers In C++

Numbers In C++

We use primitive data types such as int, short, long, float and double, etc. The number data types, their possible values and number ranges have been explained while discussing C++ Data Types.

Input:

#include <iostream>

using namespace std;

int main () {

   // number definition:

   short  s;

   int    i;

   long   l;

   float  f;

   double d;

  

   // number assignments;

   s = 10;     

   i = 1000;   

   l = 1000000;

   f = 230.47; 

   d = 30949.374;

  

   // number printing;

   cout << "short  s :" << s << endl;

   cout << "int    i :" << i << endl;

   cout << "long   l :" << l << endl;

   cout << "float  f :" << f << endl;

   cout << "double d :" << d << endl;

   return 0;

}

 Output:-

Random Number in C++

Random Number in C++

Definition:-

There are many cases where you will wish to generate a random number. There are actually two functions you will need to know about random number generation. The first is rand(), this function will only return a pseudo random number. The way to fix this is to first call the srand() function.

Following is a simple example to generate few random numbers. This example makes use of time() function to get the number of seconds on your system time, to randomly seed the rand() function –

Program:-

Input:-

#include <iostream>

#include <ctime>

#include <cstdlib>

using namespace std;

int main () {

   int i,j;

   // set the seed

   srand( (unsigned)time( NULL ) );

   /* generate 10  random numbers. */

   for( i = 0; i < 10; i++ ) {

      // generate actual random number

      j = rand();

      cout <<" Random Number : " << j << endl;

   }

   return 0;

}

Output:-

Output 2:

Adding Integer Program in C++

                        Adding Integer Program in C++

                                                     Program Input:-

#include <iostream>

#include <ctime>

#include <cstdlib>

using namespace std;

int main () { // Start Main Function

  

       int Number1; // First Integer to Add

       int Number2; // Secong Integer to Add

       int Sum; // Add Sum of Integer one And Number two

       cout << " Enter First Number" << endl;

       cin >> Number1;

       cout << "Enter Second Numbre"<<endl;

       cin >> Number2;

       Sum = Number1 + Number2;  // Add the number And store sum

       cout << "Sum is " << Sum << endl;

               

} // End Main Function

OutPut:-

Math Operations in C++

Definition:-

In addition to the various functions you can create, C++ also includes some useful functions you can use. These functions are available in standard C and C++ libraries and called built-in functions. These are functions that can be included in your program and then use.

C++ has a rich set of mathematical operations, which can be performed on various numbers. Following table lists down some useful built-in mathematical functions available in C++.

Operations:

Sr.No	Function & Purpose
1	double cos(double); This function takes an angle (as a double) and returns the cosine.
2	double sin(double); This function takes an angle (as a double) and returns the sine.
3	double tan(double); This function takes an angle (as a double) and returns the tangent.
4	double log(double); This function takes a number and returns the natural log of that number.
5	double pow(double, double); The first is a number you wish to raise and the second is the power you wish to raise it t
6	double hypot(double, double); If you pass this function the length of two sides of a right triangle, it will return you the length of the hypotenuse.
7	double sqrt(double); You pass this function a number and it gives you the square root.
8	int abs(int); This function returns the absolute value of an integer that is passed to it.
9	double fabs(double); This function returns the absolute value of any decimal number passed to it.
10	double floor(double); Finds the integer which is less than or equal to the argument passed to it.