C lecture 3 control statements slideshare
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The document discusses different types of loops in programming languages that are used for repetition of tasks. It describes while, do-while and for loops as the three main types of loops. While and do-while loops are conditional loops that check a condition each time before repeating the code block. For loops allow repetition for a set number of times using three expressions for initialization, condition and increment. Some examples are provided to demonstrate the use of these loops to print numbers from 1 to 10.
C lecture 3 control statements slideshare
- 1. Gagan Deep Rozy Computech Services 3rd Gate, K.U., Kurukshetra-136119 M- 9416011599 Email – [email protected]
- 2. Looping Suppose we want to display hello on output screen five times in five different lines. We might think of writing either five printf statements or one printf statement consisting of constant “hellon” five times. What if we want to display hello 500 times? Should we write 500 printf statement or equivalent ? Obviously not. It means that we need some programming facility to repeat certain works. Such facility in Programming Languages is available in the form Looping Statements.
- 3. Looping Loops are used to repeat something. Repetition of block of code. If program requires that group of instructions be executed repeatedly is known as looping. Looping is of two types Conditional Unconditional Conditional Looping: Computation continues indefinitely until the logical condition is true. Unconditional Looping : The number of repetition known in advance or repetition is infinite.
- 5. Types of Loops Conditional Loops While Loop – Pre Condition Loop – Entry Time Conditional Loop Do-While Loop – Post Condition Loop – Exit Time Conditional Loop Unconditional Loop For Loop – Counted Loops Uncounted Loop – Infinite loop Uncounted Loop –infinite loop controlled by control statements.
- 6. while Statement The while statement is used to carry out looping operations, in which a group of statement is executed repeatedly, until some condition has been satisfied. The general form of statement is while (test expression) statement to be executed; or while (test expression) { statements to be executed }
- 7. Program 1-4 First 10 Natural Numbers #include <stdio.h> void main() { int i=0; while(i<=9) // i<10 printf(“%d”, i++); }/*here we can’t use ++i – that gives different result*/ //only a statement #include <stdio.h> void main() { int i=0; while(i<=9) // i<10 { printf(“%dn”, i); i++; }//compound statement } //we also can use ++i #include <stdio.h> void main() { int i=10; while(i<=9) // i<10 { printf(“%d”, i); i++; } // doesn’t work body of loop } #include <stdio.h> void main() { int i=9; while(i>=0) // i>-1 { printf(“%d”, i); i--; } //--i }//decrement – decreasing order
- 8. do…..while Statement When a loop is constructed using the while statement, the test for continuation of the loop carried out at the beginning of each pass. Sometimes, however it is desirable to have a loop with the test for continuation at the end the end of each pass. This can be accomplished by do..while statement. The general form of statement is do Statement; //single statement while (expression); or do { statements to be executed } while (expression);
- 9. Program 5-8 First 10 Natural Numbers #include <stdio.h> void main() { int i=0; do printf(“%d”, i++); while(i<=9); } #include <stdio.h> void main() { int i=0; do {printf(“%dn”, i); i++; } while(i<=9) ; } #include <stdio.h> void main() { int i=10; do //first execute then check { printf(“%d”, i); i++; } while(i<=9) ; } // prints 10(execute one time) #include <stdio.h> void main() { int i=9; do{ printf(“%d”, i); i--; } while(i>=0) ; }
- 10. for Statement The for statement is the third and perhaps the most commonly used looping statement in C. This statement includes an expression that specifies an initial value for an index, another expression that determines whether or not the loop is continued, and a third expression that allows the index to be modified at the end of each pass. The general form of statement is for (expr1; expr2; expr3) statement; or { statements }
- 11. Print 1 to 10 Program 9-12 #include<stdio.h> #include<stdio.h> void main() void main() {int i; { for(i=1;i<=10;i++) for(int i=1;i<=10;++i) printf(“%d”,i); } printf(“%d”,i); } #include<stdio.h> void main() { for(int i=1;i<=10;i=i+1) printf(“%d”,i); } #include<stdio.h> void main() {int i=1; for( ; i<=10; ) { printf(“%d”,i); i++ ; } }//you can also use ++i
- 12. Program 13-16 #include<stdio.h> void main() {for(int i=0;i<5;i++) { } } // i goes to 5 only #include<stdio.h> void main() { for(i=0;i<5;i++); } // i goes to 5 only Comma Operator #include<stdio.h> void main() { for(i=0,j=0;i<5;i++, j++) { statement1; statement2; statement3; } #include<stdio.h> void main() {int i = 0; for( ; ;) { statements; if(breaking condition) break; i++; }
- 13. Program 17-18 Reverse Number #include<stdio.h> void main() {n, r, rn=0; scanf(“%d”, &n); while (n!=0) { r=n%10; n=n/10 ; rn=rn*10+r; } printf(“Reverese Number =%d”, rn); } Palindrome Number #include<stdio.h> void main() {n, r, T, rn=0; scanf(“%d”, &n); T=n; while (T!=0) { r=T%10; T=T/10 ; rn=rn*10+r; } if (rn==n) printf(“Palindrome Number); else printf(“Non-Palindrome Number); }
- 14. Program 19 Prime Number #include<stdio.h> void main() {n, i; scanf(“%d”, &n); while (n % i != 0) i++; if (n==i) printf(“%d is prime”, n); }
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