CP01: Basics of C Programming

C Basics

Mayank Abhishek

Basically C

You need a text editor to write a C ProgramEg: Notepad, VI

You need a compiler to compile your program to produce an executable file.Eg: TurboC, GCC

The version of C used in our college is ANSI C Compilers for ANSI C are Microsoft Visual C++,

GCC etc.

A Sample C Program

#include <stdio.h> int main(void){ printf("Hello, World!\n"); return (0);}

A C Program01: /* Program to calculate the product of two numbers. */02: #include <stdio.h>03:04: int a,b,c;05:06: int product(int x, int y);07:08: int main()09: {10: /* Input the first number */11: printf("Enter a number between 1 and 100: ");12: scanf("%d", &a);13:14: /* Input the second number */15: printf("Enter another number between 1 and 100: ");16: scanf("%d", &b);17:18: /* Calculate and display the product */19: c = product(a, b);20: printf ("%d times %d = %d\n", a, b, c);21:22: return 0;23: }24:25: /* Function returns the product of its two arguments */26: int product(int x, int y)27: {28: return (x * y);29: }

Comments

Comments are beauty marks for a program

// This is a single line comment

/* This is a multiline comment */

Multiline Comments cannot be nested

Incorrect Usage of Comment

/* This is an incorrect usage of a comment

/* Hello This Comment Is Wrong */

*/

Queer Comments

/*

// Hello This Comment Is Queer

*/

// Hello //This //Comment //Is //Queer

A C Program01: // Program to calculate the product of two numbers. 02: #include <stdio.h>03:04: int a,b,c;05:06: int product(int x, int y);07:08: int main()09: {10: // Input the first number 11: printf("Enter a number between 1 and 100: ");12: scanf("%d", &a);13:14: // Input the second number 15: printf("Enter another number between 1 and 100: ");16: scanf("%d", &b);17:18: // Calculate and display the product 19: c = product(a, b);20: printf ("%d times %d = %d\n", a, b, c);21:22: return 0;23: }24:25: // Function returns the product of its two arguments 26: int product(int x, int y)27: {28: return (x * y);29: }

A Wrong C Program01: /* Program to calculate the product of two numbers. */02: #include <stdio.h>03:04: int a,b,c;05:06: int product(int x, int y);07:08: int main()09: {10: /* Input the first number *//*11: printf("Enter a number between 1 and 100: ");12: scanf("%d", &a);13:14: /* Input the second number */15: printf("Enter another number between 1 and 100: ");16: scanf("%d", &b);17:18: /* Calculate and display the product */19: c = product(a, b);20: printf ("%d times %d = %d\n", a, b, c);21:22: return 0;23: }24:25: /* Function returns the product of its two arguments */26: int product(int x, int y)27: {28: return (x * y);29: }

Preprocessor Directives

The C preprocessor (cpp) is the preprocessor for the C programming language.

The preprocessor handles directives for source file inclusion (#include), macro definitions (#define), and conditional inclusion (#if).

#include

#include <stdio.h>

#include ”myfile.h”

#define

#define PI 3.14159

#define SQR(x) ((x) * (x))

Be Careful with Macros!

#define SQR(x) (x * x)

Replacements:

SQR(5) : 5 * 5 = 25

SQR(A) : A * A = A2

SQR(5+5) : 5 + 5 * 5 + 5 = 35

Variables

int a; // a = 5

int a, b; // a = 5, b= 10

float a; // a = 12.18

double a; // a = 12.18

char a; // a = 'Z'

Suggest A Variable Type for:

Roll Number Grade obtained in a course Area of a circle Value of PI

Integer Airthmetic

5 + 5 = 10

10 / 5 = 2

9 / 5 = 1

23 / 7 = 3

Find the value of:

24 / 7 * 2 + 11 / 2

Find the value of:

24 / 7 * 2 + 11 / 23 * 2 + 5

6 + 511

Functions

26: int product(int x, int y)27: {28: return (x * y);29: }

printf

printf(format string, print list);

printf(format string);

Eg: printf(“The result is %lf ”, kms);

scanf

scanf (format string, input list);

Eg: scanf (“%c%d”,&letter, &age);

New C Program

01: /* Computes and Displays the area and circumference of a circle*/02: #include <stdio.h>03: #define PI 3.1415904: 05: int main ( void )06: {07: double radius, area, circum;08: printf (“Enter the radius of the circle : ”);09: scanf (“%lf”, &radius);10: /* Calculate the area */11: area = PI * radius * radius;12: /* Calculate the circumference*/13: circum = 2 * PI * radius;14: printf(“ \n Area is: %f \n Circumference: %f”, area, circum);15: return (0);16: }

Arithmetic Operators

5 + 5 = 10

3 2 = 1

10 / 5 = 2

9 * 5 = 45

23 % 7 = 2

++a or a++ : a = a + 1

a or a : a = a 1

Relational Operators

A > B

A < B

A == B

A != B

A >= B

A <= B

Boolean Operators

NOT : !A

OR : A || B

AND : A && B

Another New C Program

01: /* Finds if a person can vote or not */02: #include <stdio.h>03: #define VOTING_AGE 1804: 05: int main ( void )06: {07: int age;08: printf (“Enter the age : ”);09: scanf (“%d”, &age);10: if (age > VOTING_AGE)11: printf (”Person can vote.”);12: else13: printf (”Person cannot vote.”);14: 15: return (0);16: }


01: /* Finds if a person can vote or not */02: #include <stdio.h>03: #define VOTING_AGE 1804: 05: int main ( void )06: {07: int age;08: printf (“Enter the age : ”);09: scanf (“%d”, &age);10: if (age >= VOTING_AGE)11: printf (”Person can vote.”);12: else13: printf (”Person cannot vote.”);14: 15: return (0);16: }


01: /* Finds the largest of three numbers */02: #include <stdio.h>03: 04: 05: int main ( void )06: {07: int a, b , c;08: printf (“Enter the values of a, b, c : ”);09: scanf (“%d %d %d”, &a, &b, &c);10: if (a >= b && a >= c) printf(”%d is largest”, a);11: if (b >= a && b >= c) printf(”%d is largest”, b);12: if (c >= a && c >= b) printf(”%d is largest”, c);13: return (0);14: }


01: /* Finds the largest of three numbers */02: #include <stdio.h>03: 04: 05: int main ( void )06: {07: int a, b , c;08: printf (“Enter the values of a, b, c : ”);09: scanf (“%d %d %d”, &a, &b, &c);10: if (a >= b)11: if (a >= c) printf(”%d is largest”, a);12: else printf(”%d is largest”, c);13: else if (b >= c) printf(”%d is largest”, b);14: else printf(”%d is largest”, c);15: return (0);16: }


01: /* Finds the largest of three numbers */02: #include <stdio.h>03: 04: 05: int main ( void )06: {07: int a, b , c;08: printf (“Enter the values of a, b, c : ”);09: scanf (“%d %d %d”, &a, &b, &c);10: if (a >= b)11: {12: if (a >= c) printf(”%d is largest”, a);13: else printf(”%d is largest”, c); 14: }15: else16: {17: if (b >= c) printf(”%d is largest”, b);18: else printf(”%d is largest”, c);19: }20: return (0);21: }

CP01: Basics of C Programming

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