Switch code for Lab 4.2 switch (input) { /* input is a variable that we will test. */ case 'M': printf("The prefix is equal to 1E6.\n"); break; case 'k': printf("The prefix is equal to 1E3.\n"); break; case 'm': printf("The prefix is equal to 1E-3.\n"); break; case 'u': printf("The prefix is equal to 1E-6.\n"); break; case 'n': printf("The prefix is equal to 1E-9.\n"); break; default: printf("Error! You must enter a valid amount.\n"); }

UNIT 5 ET156 Introduction to C Programming

Sample Conditions Table 4-2

Figure 5.1 Flow Diagram of Loop Choice Process

Types of Loops Table 5.1

Counter-Controlled Loops Used when you know the number of times the loop must execute General steps: 1. Set loop control variable to 0 2. Loop control variable < final value Execute statements Increase loop control variable by 1 For loop is best choice, but while loop will work!

Compound Assignment Operators Increment: i = i + 1; i += 1; ++I; i++; Decrement: i = i -1; i -= 1; --I; i--;

Figure 5.6 Comparison of Prefix and Postfix Increments

while Loop Style while (condition is true) { Statements to be repeated; Counter updated; } while (count <= 10){ Statements to be repeated; count++; }

Sum & Average with a while Loop count=0, sum=0; while (count < 10){ printf(Enter score: ); scanf(%d, &quiz); sum = sum + quiz; count++; } ave = sum / count;

Perform a known number actions with a while Loop product=0; multiplier=5; multiplicand=3; ctr=0; while (ctr < multiplier){ product += multiplicand; count++; }

for Loop Style for ( counter start status; condition is true; update counter; ) { Statements to be repeated; } for (i=0 ;i <= 10; i++){ Statements to be repeated; }

Sum & Average with a for Loop sum=0; for (i=0; i < 10; i++;){ printf(Enter score: ); scanf(%d, &quiz); sum = sum + quiz; } ave = sum / count;

Perform a known number actions with a for Loop product=0; multiplier=5; multiplicand=3; for (i=0; i < multiplier; i++;){ product += multiplicand; }

Off by One Errors This loop executes n+1 times: for (count = 0; count <= n; ++count) sum += count; Always test at the loop boundaries to verify the loop does the right thing.

Debugger Debugger allows: Single-step execution Setting breakpoints on a statement Variable inspections

Diagnostic Calls Use printf to output intermediate results. Define a constant named DEBUG and use a conditional: #define DEBUG 1 if (DEBUG) printf("*** score is %d, sum is %d\n", score, sum);

Common Errors Forgetting to use curly braces around multiple steps Termination condition never met (infinite loop) Mistyping an equality operator (==) as an assignment operator (=) Confusing do-while and while Mistakes related to operator precedence Avoid increment, decrement, and compound assignment operators in complex expressions. Use parentheses to control evaluation order.