if () else statement, switch statement, while () loop, do…while() loop and for( ; ; ) loop 1

if() and if()…else statement In C language the using structure to write any condition by if() is: In C language the using structure to write any condition by if() is: Syntax: if (condition) { statements to execute; } 2 Syntax: if (condition) { statements to execute; } else { statements to execute; }

Continue: Example: Write a C program to solve this problem: enter a student number and his grade, then print classification according the following values: grade < 60 then print “ fail” 60 <= grade < 70 then print “ pass” 70 <= grade < 80 then print “ good” 80 <= grade < 90 then print “ very good” 90 <= grade <=100 then print “ excellent” 3

#include void main() { int id; float grade; printf(“enter student number: ”); scanf(“%d”, &id); printf(“enter student grade: ”); scanf(“%f”, &grade); if (grade <= 60) printf(“%d grade is faile\n”, id); if (grade >= 60) && (grade < 70) printf(“%d grade is pass\n”, id); if (grade >= 70) && (grade < 80) printf(“%d grade is good\n”,id); if (grade >= 80) && (grade < 90) printf(“%d grade is very good\n”, id); if (grade >= 90) && (grade <=100) printf(“%d grade is excellent\n”, id); } 4

#include void main() { int id; float grade; printf(“enter student number: ”); scanf(“%d”, &id); printf(“enter student grade: ”); scanf(“%f”, &grade); if (grade <= 60) printf(“%d grade is faile\n”, id); else if (grade >= 60) && (grade < 70) printf(“%d grade is pass\n”, id); else if (grade >= 70) && (grade < 80) printf(“%d grade is good\n”,id); else if (grade >= 80) && (grade < 90) printf(“%d grade is very good\n”, id); else if (grade >= 90) && (grade <=100) printf(“%d grade is excellent\n”, id); else printf(“out of the range”); } 5

Another example: write a program to print the name of a day’s week (i.e. we have 7 days in a week numbered from 0 to 6) according the following table: 0 Saturday 1 Sunday 2 Monday 3 Tuesday 4 Wednesday 5 Thursday 6 Friday 6

#include void main() { int n; printf(“ Enter the day number: ”); scanf(“%d”,&n); if (n == 0) printf(“\n Saturday”); if (n == 1) printf(“\n Sunday”); if (n == 2) printf(“\n Monday”); if (n == 3) printf(“\n Tuesday”); if (n == 4) printf(“\n Wednsday”); if (n == 5) printf(“\n Thursday”); if (n == 6) printf(“\n Friday”); } 7

Switch() statement: You can use switch() to represent if() not if () else. It is very simple to chose one thing from a set of choices have the same type. Syntax: switch( var ) { case v1: statement; break; case v2: statement; break;. default : statement; } 8

Example: solve the same last program by using switch. #include void main() { int n; printf(“ Enter the day number: ”); scanf(“%d”,&n); switch ( n ) { case 0: printf(“\n Saturday”); break; case 1: printf(“\n Sunday”); break; case 2: printf(“\n Monday”); break; case 3: printf(“\n Tuesday”); break; case 4: printf(“\n Wednsday”); break; case 5: printf(“\n Thursday”); break; case 6: printf(“\n Friday”); break; default: printf(“\n out of range ….”); } } 9

Ass. Write a program to print a menu on the output screen. But your choices are character. Using if() and switch() at each time. Due next lecture. 10

Loops: you can use loop when you have a number of iteration, or you need to continue a such process until enter special character (like Y or N) or number (like -1) to exit. There are a different kind of loop in C program like while(), do…while() and for() 11

While () loop Syntax: initialize variable; while(condition) { statements; increment or decrement variable; } 12

Example: write a program to enter id_number of students and print what you read until enter (N or n). #include void main( ) { char ch; int id; printf(“ Do you want to enter a student numder?(Y\N) ”); scanf(“%c”,&ch); while((ch !=‘N’)&&(ch !=‘n’)) { printf(“\n id number is: ”); scanf(“%d”, &id); printf(“id= %d \n”,id); printf(“ Do you want to enter a student numder?(Y\N) ”); scanf(“%c”,&ch); } printf(“\n end the program”); } 13

do … while() loop Syntax: initial_value; do { statements; increment or decrement; } while(condition); 14

Ass. Write the same last program by using do… while() Due next lecture 15

for () loop Syntax: for (initial value; condition; increment or decrement variable) { statements; } 16

Example: write a program to print this shape. * * * * * * * * * * 17

#include void main( ) { int i, j, k, n; printf(“\n enter number of lines: ”); scanf(“%d”, &n); for (i=1; i <= n; i++) { for(j=n; j > i; j--) { printf(“ ”); } for (k=1; k<= i; k++) { printf(“*”); } printf(“\n”); } 18