CECS 121 EXAM 1

/* C Programming for the Absolute Beginner */

// by Michael Vine#include <stdio.h>#include <stdlib.h>main(){

printf(“\nC you later\n”);system(“pause”);

}

Serve to control program execution and functionality. Must end with a semicolon(;) with the exception of:

Comments: /* */ Preprocessor Directives: #include or

#define Begin and end program identifiers:

{ } Function definition beginnings: main()

Functions allow you to group program statements under one name

C is case-sensitive so main(), MAIN(), and Main() are all different

The main function is special because the values it returns are returned to the operating system

Most main functions in this course do not take or pass information to the operating system

Definition: Escape sequences are specially sequenced characters used to format output

\” Ex: printf(“ \ “This is quoted text \ “ “)

\’ Ex: printf(“ \n A single quote looks like \’ \n”);

\* *\ Comment Block

#include <stdio.h> Using a directive to include a header file

stdio.h = standard input output header file

stdlib.h = ‘system’ commands

A computer’s long-term memory is called nonvolatile memory and is generally associated with mass storage devices, such as hard drives.

A computer’s short term memory is called volatile memory. It loses is data when power is removed from the computer

To declare a constant (read only) value:const int x = 20;const float PI = 3.14;

TYPE SIZE VALUES

bool 1 byte true (1) or false (0)

char 1 byte ‘a’ to‘z’ , ‘A’ to ‘Z’, ‘0’ to ‘9’, space, tab, and so on

int 4 bytes -2,147,483,648 to 2,147,483,647

short 2 bytes -32,768 to 32,767

long 4 bytes -2,147,483,648 to 2,147,483,647

float 4 bytes + - (1.2 x 10^-38 to 3.4 x 10^38)

double 8 bytes +- (2.3 x 10^-308 to -1.7 x 10^308)

Can you explain what the code is doing?

Character - %c Integer - %d Float (decimal)- %f String - %s Printf Format Tags:

%[flags][width][.precision][length]specifier

%[.precision]specifer -> %.2f

int main(){ printf (“%c %c \n", 'a', 65); printf (" %10d \n", 1977); printf ("%010d \n", 1977); printf ("floats: %4.2f \n", 3.1416); printf ("%s \n", "A string"); printf(“%f \n”, 55.55);return 0; }

}

printf (“%c %c \n", 'a', 65); aAprintf ("%d %ld\n", 1977, 650000L); 1977650000printf (" %10d \n", 1977);

1977printf ("%010d \n", 1977); 0000001977printf ("floats: %4.2f \n", 3.1416); 3.14

printf ("%s \n", "A string"); A string

Can you create a tabular data using printf?

Syntaxscanf(“conversion specifier”, variable);

#include <stdio.h>

main(){

int iOperand1 = 0;int iOperand2 = 0;

printf(“\n Enter first operand: “);scanf(“%d”, &iOperand1);printf(“\n Enter second operand: “);scanf(“%d”, &iOperand2);

printf(“The result is %d \n”, 24/(iOperand1 * iOperand2)+6/3);

}

#include <stdio.h>

main(){

int x = 4;int y = 9;

int result1, result2;

result1 = y/x;result2 = y%x;

printf(“The result is %d.%d \n”, result1, 25*result2);

}

Do you know the answers to these?A. !( 1 || 0 ) B. !( 1 || 1 && 0 ) C. !( ( 1 || 0 ) && 0 )

A. !( 1 || 0 ) ANSWER: 0

B. !( 1 || 1 && 0 ) ANSWER: 0 (AND is evaluated before OR)

C. !( ( 1 || 0 ) && 0 ) ANSWER: 1 (Parenthesis are useful)

Can you write code that will ask a user to enter a number 1 , 2 , or 3 and print out the following:

#include <stdio.h>

int main(){ int a; printf (“Enter one of the following: %d, %d, or %d\n”, 1, 2, 3); scanf(“%d”, &a);if(a==1|| a==2|| a ==3){

if(a==1){printf(“\n %d is the loneliest number \n“, 1); }

if(a==2){printf(“\n%d is better than %d \n”,2,1);

}if(a==3){

printf(“\n%d \’ s a crowd \n”,3); }

elseprintf(“Sorry, you entered an invalid value\n”);

return 0; }

while ( condition ) { Code to execute while the condition is true }

Quiz: Can you write a program that prints xwhile x increments from 0 to 10?

x++; Tells the function to use the current value of x and increment it by 1.++x; Increment the value of x by 1 and use the new value for calculations.

x--; Tells the function to use the current value of x and decrease its value by 1.--x; Decrease the value of x by 1 and use the new value for calculations.

x=0;printf(“The Value of x is: %d”, x++);printf(“\n The Value of x is: %d”,++x);

Would results in: The Value of x is: 0The Value of x is: 2

Often used when the # of iterations is already known.

Contains 3 separate expressions:1. Variable initialization2. Conditional expression3. Increment/Decrement

Try writing a program with a for loop that counts down from 10 seconds.

#include <stdio.h>

main(){ int x=0; for(x=10; x>=0; x--) { printf("%d \n", x); } system("pause");}

break;Used to exit a loop. Once this statement is executed the program will execute the statement immediately following the end of the loop.

continue;Used to manipulate program flow in a loop. When executed, any remaining statements in the loop will be skipped and the next iteration of the loop will begin

Function Prototype Syntax

return-type function_name ( arg_type arg1, ..., arg_type argN)

Function Prototypes tell you the data type returned by the function, the data type of parameters, how many parameters, and the order of parameters

Function definitions implement the function prototype

Where are function prototypes located in the program?

Where do you find function definitions?

Where are function prototypes located in the program? Answer: before the Main(){} Function!

Function Definitions are self contained outside of the Main(){} function

#include <stdio.h> int mult ( int, int );

int main() { int x; int y;

printf( "Please input two numbers to be multiplied: " ); scanf( "%d", &x ); scanf( "%d", &y ); printf( "The product of your two numbers is %d\n", mult( x, y ) ); getchar();

}

int mult (int a, int b) { return a * b; }

#include <stdio.h> Void printReportHeader();

main(){

printReportHeader;}

void printReportHeader(){

printf(“\n Column1\tColumn2\tColumn3\tColumn4 \n”);}

#include <stdio.h>

void printNumbers();int iNumber;

main() { int x;

for(x=0, x<10,x++){printf(“\n Enter a number:”);scanf(“%d”, &iNumber);printNumbers();

}}

void printNumbers(){

printf(“\n Your number is: %d \n”, iNumber);}

Variable scope defines the life time of a variable

Local Scope: defined within functions and loses scope after function is finished. Can reuse in other functions (ex. p.123)

Global Scope: defined outside of functions and can be accessed by multiple functions