Download Lecture 3: Structured Programming and Control Structures in C - Prof. Lan Xiang and more Study notes Electrical and Electronics Engineering in PDF only on Docsity!
EE114:
Programming Concepts for Engineers
Lecture 3
Overview
n Structured programming
n Selection structure
n if statement
n if-else statement
n switch statement
Structured Programming
n Sequence structure
n Selection structure
n if statement
n if-else statement
n switch statement
n Repetition structure
n while loop
n do-while loop
n for loop
n All these 3 structures together, selection, sequence, and
repetition, are referred as control structures. All C programs
could be written in terms of these three types of control
structures only and we call this structured programming.
If statement
if (expression)
statement;
Expression
Statement
True
False
Exit
Entry
if (grade < 60)
printf("Sorry, you failed this class!\n");
flowchart
if (expression) {
statement_1;
statement_2;
……
statement_n;
}
If statement with compound statement
if (a<5) {
printf("a is less than 5");
printf("Sorry, data is not correct!\n");
If-else statement
if (expression)
statement0;
else
statement1;
Expression Statement
True
False
Exit
Entry
Statement
if (a>=0)
printf(“Positive!\n”);
else
printf(“Negative!\n”);
If-else with compound statement
if (expression) {
statement0;
statement1;
else {
statement3;
statement4;
if (a>=0){
printf(“Positive!\n”);
x=a;
else {
printf(“Negative!\n”);
x=-a;
Relational Operators
n > if (c>b) if c is great than b
n >= if (c>=b) if c is great than or equal to b
n < if (c<b) if c is less than b
n <= if (c<=b) if c is less than or equal to b
n == if (c==b) if c is equal to b
n != if (c!=b) if c is not equal to b
#include <stdio.h> #include <math.h> /* math libaray is included for sqrt() function */
int main( void ) { float a, b, c, delta, div;
printf( "Enter Value for Coefficient 'a', 'b', 'c' : "); scanf( "%f %f %f", &a, &b, &c);
delta = bb - 4.0 * a c; div = 2.0 * a;
if( a == 0 ) { /* if a is 0, only one single root / printf( "Single root = %g\n", -c/b) ; } else { /if a is not 0, then we have two roots / if (delta >= 0.0) { / if roots are real/ printf( "Roots are real\n"); printf( "Root1 = %g\n ", (-b + sqrt(delta))/div ); printf( "Root2 = %g\n ", (-b - sqrt(delta))/div ); } else { / if roots are complex */ printf( "Roots are complex\n"); printf( "Root1 = (%g) + i(%g)\n", - b/div, sqrt(-delta)/div ); printf( "Root2 = (%g) - i(%g)\n", - b/div, sqrt(-delta)/div ); } } return 0 ; } 14
Enter value for Coefficient ‘a’, ‘b’, ‘c’ : 6 3 -
Roots are real
Root1 = 0.
Root2 = -1.
Enter value for Coefficient ‘a’, ‘b’, ‘c’ : 0 6 4
Single root = -0.
Enter value for Coefficient ‘a’, ‘b’, ‘c’ : 6 3 4
Roots are complex
Root1 = (0.25) + i(0.777282)
Root2 = (0.25) - i(0.777282)
