Tutorial No. 5 - Solution (Decision Making and Branching)

Transcription

1 Tutorial No. 5 - Solution (Decision Making and Branching) 1. Explain if...if ladder with flowchart [7] The if ladder is a way of putting together ifs together when multipath decisions are involved. A multipath decision is a chain of ifs in which the statement associated with each is an if. It takes the following general form: if ( condition 1 ) statement 1; if ( condition 2 ) statement 2; if ( condition 3 ) statement 3; if ( condition n ) statement n; default-statement; The conditions are evaluated from top to downwards. As soon as a true condition is found, the statement associated with it is executed and the control is transferred to the statement-x, skipping the rest of the ladder. When all the n conditions become false, then the final containing the default-statement will be executed. The flowchart of if ladder is shown below:

2 if ( marks >79 ) grade = Honours ; if ( marks>59 ) grade = First Division ; if ( marks>49 ) grade = Second Division ; if ( marks>39 ) grade = Third Division ; grade = Fail ; printf( %s,grade ); 2. Give output of following a)void main() int n=6, t=1; for(;n<10;n=n+2) printf( %d %d\n,n,++ t); b) void main() int a=3 b=5,c,*p,*q; p=&b; q=&a; c=*p % *q; ++(*p); printf ( %d %d,*p,*q); printf ( \n %d %d, c,b); [7] What will be the output of following program? main() int x = 10, y, z; z = y = x ; y - = x-- ; z - = --x ; x - = --x x-- ; printf( y = %d z = %d x = %d, y, z, x) ; y = 0 z = 2 x = 6 4. Write a C program to determine a given number is odd or even and print the following message NUMBER IS EVEN Or NUMBER IS ODD (i) Without using option. #include<stdio.h> #include<conio.h> [2] [5]

3 void main() int n; printf("enter the number"); scanf("%d",&n); if( n%2 == 0 ) printf( NUMBER IS EVEN ); if( n%2!= 0 ) printf( NUMBER IS ODD ); getch(); (ii) With option. #include<stdio.h> #include<conio.h> void main() int n; printf("enter the number"); scanf("%d",&n); if( n%2 == 0 ) printf( NUMBER IS EVEN ); printf( NUMBER IS ODD ); getch(); 5. Write a C program to evaluate the square root for five numbers using the goto statement. [5] #include<stdio.h> #include<conio.h> void main() int n, s, i=1; label: printf("enter the number"); scanf("%d",&n); s=sqrt(n); printf( %d\n,s);

4 i++; if(i<=5) goto label; getch(); 6. Write short note on 1. if.. statement The if.. statement is an extension of the simple if statement. The general form is: if (test expression) True-block statement(s) False-block statement(s); If the test expression is true, then the true-block statement(s), immediately following the if statement are executed; otherwise, the false-block statement(s) are executed. In either case, either true-block or false-block will be executed, not both. [7] printf( Enter two numbers ); scanf( %d%d,&a, &b); if(a>b) printf( a is Maximum ); printf( b is Maximum );

5 2. Nested if.. statement When a series of decisions are involved, we may have to use more than one if... statement in nested form as shown below: Here, if the condition 1 is false then it skipped to statement 3. But if the condition 1 is true, then it tests condition 2. If condition 2 is true then it executes statement 1 and if false then it executes statement 2. Then the control is transferred to the statement x. This can also be shown by the following flowchart: printf( Enter three numbers ); scanf( %d%d,&a, &b,&c); if(a>b) if(a>c) printf( a is Maximum ); printf( c is Maximum );

6 if(b>c) printf( b is Maximum ); printf( c is Maximum ); 7. Explain switch statement with example. [5] The switch statement tests the value of a given variable (or expression) against a list of case values and when a match is found, a block of statements associated with that case is executed. The general form of switch statement is as follows: switch (expression) case value-1: block-1 case value-2: block-2 case value-3: block-3.. default: default-block The expression is an integer expression or characters. value1, value-2, are constants or constant expressions and are known as case labels. Each of these values should be unique within a switch statement. block-1, block-2, are statement lists and may contain zero or more statements. When the switch is executed, the value of the expression is successfully comaredagainst the values value-1, value-2,. If a case is found whose value matches with the value of the expression, then the block of statements that follows the case are executed. The break statement at the end of each block signals the end of a particular case and causes an exit from the switch statement, transferring the control to the statement following the switch. The default is an optional case. When present, it will be executed if the value of the expression does not match with any of the case values. If not present, no action takes place if all matches fail and the control goes to the statement following the switch. The selection process of switch statement is shown below.

7 index = marks/10; switch (index) case 10: case 9: case 8: grade = Honours ; case 7: case 6: grade = First Division ; case 5: grade = Second Division ; case 4: grade = Third Division ; default: grade = Fail ; printf( %s,grade);

8 8. Explain goto statement with example [5] C supports goto statement to branch unconditionally from one point to another in the program. The goto requires a label in order to identify the place where the branch is to be made. A label is any valid variable name, and must be followed by a colon. The label is placed immediately before the statement where the control is to be transferred. The general form of goto and label are shown below: The label can be anywhere in the program either before or after the goto label; statement. During running of a program when a statement like goto begin; is met, the flow of control will jump to the statement immediately following the label begin;. This happens unconditionally. A goto breaks the normal sequential execution of the program. If the label is before the statement goto label;, a loop will be formed and some statements will be executed repeatedly. Such a jump is known as a backward jump. On the other hand, if the label is placed after the goto label; some statements will be skipped and the jump is known as forward jump. [Write the program of question 5]