First Program in C With Output

C Language Keywords

Variables In C

Initialize int value in declaration

Using a variable to store value

Meaningful variable name

Define three variables and use assignment operator to assign value int main() { int term; /* term used in two expressions */ int term_2; /* twice term */ int term_3; /* three times term */ term = 3 * 5; term_2 = 2 * term; term_3 = 3 * term; return (0); }

Use printf to output variable

Printing Variable Contents

Finding the limits

#include #include #include int main(void) { printf("Variables of type char store values from %d to %d", CHAR_MIN, CHAR_MAX); printf("\nVariables of type unsigned char store values from 0 to %u", UCHAR_MAX); printf("\nVariables of type short store values from %d to %d", SHRT_MIN, SHRT_MAX ); printf("\nVariables of type unsigned short store values from 0 to %u",USHRT_MAX); printf("\nVariables of type int store values from %d to %d", INT_MIN, INT_MAX); printf("\nVariables of type unsigned int store values from 0 to %u", UINT_MAX); printf("\nVariables of type long store values from %ld to %ld", LONG_MIN, LONG_MA X); printf("\nVariables of type unsigned long store values from 0 to %lu", ULONG_MAX); printf("\nVariables of type long long store values from %lld to %lld", LLONG_MIN, LLO NG_MAX);

printf("\nVariables of type unsigned long long store values from 0 to %llu", U LLONG_MAX); printf("\n\nThe size of the smallest non- zero value of type float is %.3e", FLT_MIN); printf("\nThe size of the largest value of type float is %.3e", FLT_MAX); printf("\nThe size of the smallest non- zero value of type double is %.3e", DBL_MIN); printf("\nThe size of the largest value of type double is %.3e", DBL_MAX); printf("\nThe size of the smallest non- zero value of type long double is %.3Le", LDBL_MIN); printf("\nThe size of the largest value of type long double is %.3Le\n", LDBL_ MAX); printf("\nVariables of type float provide %u decimal digits precision.", FLT_D IG); printf("\nVariables of type double provide %u decimal digits precision.", DBL _DIG); printf("\nVariables of type long double provide %u decimal digits precision.", LDBL_DIG); return 0; }

OUTPUT

Finding the size of a type

Scope of variables

value of i is 1 the value of i is 10 The Value of i is 1 The Value of i is 10

Inner variable shadows outer variable

Output

Declare global variables

Define and use Global variables

Local variable shadows global variable.

Static variable

Output

Static versus automatic variables

Output address and value

Using the & operator

Calculate an average using variable argument lists

Adding Comments

Indentation and Code Format

Without Indentation

With Indentation

Clarity

Header Files

IncludeHeader File

Newly Added Headers

External Reference

// Program in file A1.c #include void hell() { int i =60; printf("value o f i %d\n",i); }

// Program in file A2.c #include extern int i; void main() { int i =50; clrscr(); hell(); printf("value of i %d\n",i); }

output The value of variable i is 60

Data Types

Unsigned Variables

Reading Integer’s

Reading integer’s can be done through scanf void main(){ int i; scanf(“%d”,&i); printf(“i=%d”,i); }

#include int main() { printf( "%4d\n", 1 ); printf( "%4d\n", 12 ); printf( "%4d\n", 123 ); printf( "%4d\n", 1234 ); printf( "%4d\n\n", ); printf( "%4d\n", -1 ); printf( "%4d\n", -12 ); printf( "%4d\n", -123 ); printf( "%4d\n", ); printf( "%4d\n", ); return 0; }

#include int main() { printf( "%4d\n", 1 ); printf( "%4d\n", 12 ); printf( "%4d\n", 123 ); printf( "%4d\n", 1234 ); printf( "%4d\n\n", ); printf( "%4d\n", -1 ); printf( "%4d\n", -12 ); printf( "%4d\n", -123 ); printf( "%4d\n", ); printf( "%4d\n", ); return 0; }

Simple Int Calculation

Divide Integer

Sum the integers from 1 to a user- specified number

If both operands i1 and i2 are integers, the expression i1/i2 provides integer division

The atoi() function: read numeric values from the keyboard

Hexadecimal Numbers

Octal Numbers

Save Tab key into a char, you use an escape sequence

Output

#include int main() { clrscr(); // char tab='\x9C'; printf("**********"); printf("%%%\\Hello"); // printf("a%cb",tab); return 0; }

SOME % WILL BE DIMINISHED BECOZ OF “\\” output

#include int main() { clrscr(); // char tab='\x9C'; printf("**********"); printf("\?Hello\?"); // printf("a%cb",tab); return 0; }

Display the ASCII characters and their corresponding codes, from Code 32 on up to Code 127

Overflow in char and unsigned char data type Overflow means you are carrying out an operation such that the value either exceeds the maximum value or is less than the minimum value of the data type. (Definition from C & Data Structures by P.S. Deshpande and O.G. Kakde Charles River Media 2004)

Compare characters to characters in if statement #include void main() { char cResponse = '\0'; clrscr(); printf("\n\tAC Control Unit\n"); printf("\na\tTurn the AC on\n"); printf("b\tTurn the AC off\n"); printf("\nEnter your selection: "); scanf("%c", &cResponse);

Compare char variable in if statement

if (cResponse == 'a') printf("\nAC is now on\n"); if (cResponse == 'b') printf("\nAC is now off\n"); getch(); }

Using functions islower, isupper, tolower, toupper

Using functions isdigit, isalpha, isalnum, and isxdigit

Using functions isspace, iscntrl, ispunct, isprint, isgraph

Floats

C provides two main floating-point representations: float (single precision) and double (double precision ). A floating-point number has a fractional part and a biased exponent. Float occupies 4 bytes and double occupies 8 bytes.

Use the format %f for printing floating numbers

Float Basics

Define float constant value using Macro

Assignment of an integer expression to a floating-point variable. C will automatically perform the conversion from integer to floating point. A similar conversion is performed when a floating-point number is assigned to an integer.

output

To create precision with floating-point numbers

use the %E in printf() to display scientific-notation numbers

Printing floating-point numbers with floating-point conversion specifiers

Read float number and do a calculation