Program loopingExample – Calc FactorialExample – Calc Factorial (cont.)Calc Factorial – Data FlowFlow Chart ComponentsCalc Factorial – Flow chartfor loopCalculate factorialCalc Factorial – codeinit_expressionloop_expressionloop_conditionloop_condition – examplesNested for LoopsExampleCodeCode – cont.Print Factorial F(1) … F(10)Calculate Fibonacci NumbersSlide 20while loopfor loop vs while loopConvert for loop to while loopConvert for to while – Exampledo-while loopwhile and do-while loopSlide 27Slide 28Program looping•Why we need loop–Make code concise for repetitive processes•When to use loop–Run a block of code repetitively–Process multiple data using same procedure•How to use loop–for–while–doExample – Calc Factorial •Goal: computing factorial N (N!) F(N) = N! = 1 * 2 * 3 * …… N•FactF(1) = 1;F(2) = 1 * 2 = F(1) * 2;F(3) = 1 * 2 * 3 = F(2) * 3; …F(N) = F(N-1) * N;Example – Calc Factorial (cont.)F(N) = F(N-1) * N;F = F * M;F = 1; M = 1;M = M +1;When to stop?M equals to NCalc Factorial – Data FlowF(N) = F(N-1) * N;•Initial setting:M = 1; F = 1;•Main calculationF = F * M;•Stop criteriaM = N•What else increase M by 1M = M + 1;F = F * M;F = 1; M = 1;M = M +1;Flow Chart Components•Help to document program logic* Not required.Calc Factorial – Flow chartF(N) = F(N-1) * N;•Initial setting:M = 1; F = 1;•Main calculationF = F * M;•Stop criteriaM = N•What else increase M by 1M = M + 1;for loop•Format: for( init_expression; loop_condition; loop_expression ) { program statement; }•Flow:Condition satisfied?NoInitial ExpressionYesProgram statementloop expressionloop expressionCalculate factorialfor( init_expression; loop_condition; loop_expression ) { program statement; }•Correspondingly when F(N)init_expression:loop_condition:loop_expression:program statement:M = 1;M <= N;M = M + 1;F = F * M;Calc Factorial – code#include <stdio.h>int main(void){int F, N, M;F = 1;N = 10;for(M=1; M<=N; M=M +1){ F = F * M;}printf(“result is: %i \n”, F);return 0;}init_expression•Set initial values before the loop begins–Can be multiple valid C program statements, separated by comma (,)for( i = 0, j = 0; i < 10; ++i )–May be omitted if initial values have been set before•Make sure to put an empty statement with only semicolon (;)for(; i<10; i++)–Using gcc on grove.ufl.edu, you CANNOT declare variables here (different from textbook)loop_expression•Change values after the program statements in the for loop–Can be multiple valid C program statements, separated by comma (,)for(i = 0; i < 10; j++,++i )–May be omitted•put nothingfor(; i<10; )•Make sure the value for i has been changed within the for loop!loop_condition•Relational expression stating when loop continuesOperator Meaning Example== Equal to Count == 10!= Not equal to Count != 10< Less than Count < 10<= Less than or equal to Count <= 10> Greater than Count > 10>= Greater than or equal to Count >= 10loop_condition – examples1. for(count = 1;count == 10; count++) { … }2. for(count = 1; count != 10; count++) { … }3. for(count = 1; count <10; count++) { … }4. for(count = 1; count <=10; count++) { … }5. for(count = 1; count >10; count++) { … }6. for(count = 1; count >=10; count++) { … }What is the value of count after the for loop?1 2 3 4 5 6count1 10 10 11 1 1Nested for Loops•Insert a loop within the loop of anotherfor( i=1; i<10; i++){for(j=1; j<10; j++) {…;}…;}Example•If we want to print following pattern*******************************************************Print n stars at the nth linePrint 1 star at the 1st linePrint 2 stars at the 2nd linePrint 3 stars at the 3rd lineCode#include <stdio.h>int main(void){ int row, col; for (row = 1; row <= 10; row++) { for (col = 1; col <= row; col++) { printf("*"); } }}printf("\n");Code – cont.#include <stdio.h>int main(void){ int row, col, max_rows; printf("How many rows do you want to print out? \n"); scanf("%i", &max_rows); for (row = 1; row <= max_rows; row++) { for (col = 1; col <= row; col++) { printf("*"); } printf("\n"); }}Print Factorial F(1) … F(10)#include <stdio.h>int main(void){ int F, N, M; F = 1; N = 10; printf("num \t factorial \n"); for(M=1; M<=N; M=M+1) { F = F * M; printf("%i \t %i \n", M, F); } return 0;}Calculate Fibonacci Numbersinitial value:init_expression:loop_condition:loop_expression:program statement:N = 2;N <= M;N = N + 1;Fn = Fnm1 + Fnm2;Fnm1 = 1; Fnm2 = 0;What else?Fnm2 = Fnm1; Fnm1 = Fn;#include <stdio.h> int main(void) { int m = 0; int Fn = 0; int Fnm1 = 1; int Fnm2 = 0; /* print out the first two numbers */ printf("F(%i) = %i\n", 0, 1); printf("F(%i) = %i\n", 1, 1); /* print out the next 38 numbers */ for (n = 2; n < 40; n++) { /* calculate the next number and print it */ Fn = Fnm1 + Fnm2; printf("F(%i) = %i\n", n, Fn); /* update the old two numbers for next time through the loop */ Fnm2 = Fnm1; Fnm1 = Fn; } /* no error */ return 0; }while loop•Formatwhile (loop_condition) { program statement; } •FlowCondition satisfied?Program statementYesNofor loop vs while loopCondition satisfied?NoInitial ExpressionYesProgram statementloop expressionloop expressionCondition satisfied?Program statementYesNofor loop while loopConvert for loop to while loopwhile (loop_condition) { program statement; } for( init_expression; loop_condition; loop_expression ) { program statement; } program statement; loop_expression;init_expression;while(loop_condition){}Convert for to while – ExampleF = 1;N = 10;for(M=1; M<=N; M=M +1){ F = F * M;}init_expression;while(loop_condition){program statement; loop_expression;}F = 1;N = 10;M = 1;while(M<=N){}F = F * M;M = M +1;do-while loop•Formatdo { program statement } while (loop_condition);Condition satisfied?Program statementYesNowhile and do-while loop•In while loop, program statement may never be evaluated. While in do-while loop, it is evaluated at least onceCondition satisfied?Program statementYesNowhile (loop_condition) { program statement; } do { program statement } while (loop_condition);Condition satisfied?Program statementYesNoExamplep = 7; p = 7;c = 1; p = 1;do{ p = p + c; c++;} while( c<= 3 );Code 2c = 1; p = 1;while( c<= 3 ){ p = p + c; c++;}Code 1Examplep = 1; p = 6;c = 5; p = 1;do{ p = p + c; c++;} while( c<= 3 );Code 2c = 5; p = 1;while( c<= 3 ){ p = p + c; c++;}Code