1 / 19

Evaluation of the Course (Modified)

Evaluation of the Course (Modified). Assignments: 40% Assignment: My part 20% and Dr. Lam’s part 20% MY PART: (2 assignments done in lab, 10% each) A final exam: 60%;. Use of return statement.

armwood
Download Presentation

Evaluation of the Course (Modified)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Evaluation of the Course (Modified) • Assignments: 40% • Assignment: My part 20% and Dr. Lam’s part 20% • MY PART: (2 assignments done in lab, 10% each) • A final exam: 60%; CS3369 Real Time Control Software/DENG Xiaotie

  2. Use of return statement If the type of the function is not void, at least one return statement must be used. The syntax of a return statement is: return value; Here value can be a number, variable or math expression. Examples: return 0; return x; return (x+1-2*y); Purposes: 1. Terminates the function. 2. Return a value to the parent function. CS3369 Real Time Control Software/DENG Xiaotie

  3. A tricky example of return statement int f(int i) { if (i>3) { cout<<“good” return i; } else {cout<<“bad”; return -999; } } #include<iostream.h> int f(int i); void main(){ int x; x=f(5); } CS3369 Real Time Control Software/DENG Xiaotie

  4. Local Variables • Variables declared within the body of a function are its localvariables (we also say the scope of these variables is the body of this function.) (Look at an example) • Variables declared within the body of the main() function of a program is local to the main() function. • A local variable is completely unknown outside its scope. Two local variables of different scopes may have the same name. CS3369 Real Time Control Software/DENG Xiaotie

  5. An Example for Local Variables #include<iostream.h> int speed(int i) int main() { int x, y=100; x=speed(10); cout<< “The value of y inside main”<<y; return 0; } int speed(int i) { int y; y=2.1*i-0.15*i*i; cout<< “The value of y inside speed()”<<y; cout<<“\n”; return y; } Output: The value of y inside speed() 6 The value of y inside main 100 CS3369 Real Time Control Software/DENG Xiaotie

  6. Variables in parameter list • Variables declared in the parameter list of a function are called formal variables. Their scope is the body of this function. • call-by-value mechanism: by default, when a function is called, the value of the arguments are plugged in the formal parameters. More specifically, if the arguments are variables, their values not the variables themselves are plugged in. • call-by-reference mechanism (will not covered in this course) CS3369 Real Time Control Software/DENG Xiaotie

  7. An Example for Local Variables #include<iostream.h> int speed(int i) int main() { int x, y=100, j=10; x=speed(j); cout<< “The value of y inside main”<<y; return 0; } int speed(int i) { int y; y=2.1*i-0.15*i*i; cout<< “The value of y inside speed()”<<y; cout<<“\n”; return y; } Output: The value of y inside speed() 6 The value of y inside main 100 The value of j is passed to speed(), not the variable j. CS3369 Real Time Control Software/DENG Xiaotie

  8. Global Variables • Global variable: universal for the program, declared in the program outside all functions. It can be used and changed everywhere (by any function). • Try to avoid using global variables. #include<iostream.h> int g; void main() { int x,y; x=11; g=80; y= f(5); cout<<“The values of g , x and y in main()” cout<<g<<“ ”<< x<<“ ”<<y; } int f(int i) {int x=10; cout<<“The values of g and x in side f()”; cout<<g<<“ ” <<x<<“\n”; g=g+i; return g; } OUTPUT: The values of g and x in side f() 80 10 The values of g , x and y in main() 85 11 85 CS3369 Real Time Control Software/DENG Xiaotie

  9. Another Example for Global Variables The roots of a quadric equation ax2+bx+c=0 are x1= (-b+( b2-4ac))/2ac x2=x1= (-b- ( b2-4ac))/2ac include<iostream.h> float x1, x2; int flag=0; void roots(float a, float b, float c) void main(void) { roots(1.0,2.0, 1.0); if(flag == 0) cout<<“The roots are”<<x1<<x2; else cout<<“No real root”; } void roots(float a, float b, float c) { if (b*b-4*a*c>=0) { x1=(-b+sqrt(b*b-4*a*c))/(2*a*c); x2 =(-b-sqrt(b*b-4*a*c))/(2*a*c); } else flag=1; } x1, x2 and flag are used as global variables. Otherwise, roots must return two values that we do not know how to do it. CS3369 Real Time Control Software/DENG Xiaotie

  10. Global Variables vs Local Variables • If global variables and local variables have the same name, the local variables are valid within their scopes. #include<iostream.h> int g=30; void main() { int x,y, g; /*g is a local variable */ x=11; g=80; y= f(5); cout<<“The values of g , x and y in main()” cout<<g<<“ ”<< x<<“ ”<<y; } int f(int i) {int x=10; cout<<“The values of g and x in side f()”; cout<<g<<“ ” <<x<<“\n”; /*g is a global variable */ g=g+i; return g; } OUTPUT: The values of g and x in side f() 30 10 The values of g , x and y in main() 80 11 35 CS3369 Real Time Control Software/DENG Xiaotie

  11. while statement #include<iostream.h> void main() { int a; cout<<“please enter an integer in [1,9]\n”; cin>>a; while (a<1 ||a>9) { cout<<“please enter an integer in [1,9]\n”; cin>>a; } } (Demo the program in the lecture.The question was given in Lab2 as extra exercise since you have not learned while. It can be done using for in a dirty way) Syntax of while statement: while (logic_expression) { statement1; statement 2; …. } CS3369 Real Time Control Software/DENG Xiaotie

  12. Review and Exercises • variables • for statement • while statement • if statement • switch statement (optional) • while statement • functions CS3369 Real Time Control Software/DENG Xiaotie

  13. Exercises Question 1: Which of the following words can be used as variable names? 1x11, x11, xx12, _abc, name_variable, for, if, for1, 1while. Question 2. What are the outputs of the following program? #include<iostream.h> void main() { int i, j; for (i=1; i<5; i++) { for(j=1; j<=3; j++) cout<<i<<j; cout<“\n”; } } CS3369 Real Time Control Software/DENG Xiaotie

  14. Question 3. What are the outputs of the following program? #include<iostream.h> void main() { int i = 10; if(i<0) cout <<“negative”; if (i>100) cout<<“too large”; if (i>=75 && i<=100) cout<<“excellent”; } What if the initial value is 88? Question 4. What are the outputs of the following program? #include<iostream.h> void main() { int i, j; for (i=1; i<=5; i++) { for (j=1; j<=i; j++) cout<<“ ”; /* There is one space*/ cout <<“**** \n”; } } CS3369 Real Time Control Software/DENG Xiaotie

  15. Question 5. What are the outputs of the following program? #include<iostream.h> void main() { int i; i=1; while(i<=5) { cout<<i; i=i+1; } } Question 6. What are the outputs of the following program? #include<iostream.h> int max (int x, int y); void main() { int x1=100, x2=102, x3=99; int temp_max, temp_max1; temp_max=max(x1,x2); temp_max1=max(temp_max, x3); cout<<“The maximum is”; cout << temp_max1; } int max (int x, int y) { int temp=x; if (y>temp) temp=y; return temp; } CS3369 Real Time Control Software/DENG Xiaotie

  16. Question 7. What are the outputs of the following program? #include<iostream.h> int max (int x, int y, int z); void main() { int x1=100, x2=102, x3=99; int temp_max; temp_max=max(x1,x2,x3); cout<<“The maximum is”; cout << temp_max; } int max (int x, int y, int z) { int temp=x; if (y>temp) temp=y; if(z>temp) temp=z; return temp; } Question 8. What are the outputs of the following program? #include<iostream.h> int max (int x, int y, int z); void main() { int temp_max; temp_max=max(99, 102, 166); cout<<“The maximum is”; cout << temp_max; } int max (int x, int y, int z) { int temp=x; cout<<“The input numbers are”<<x<<y<<z<<“\n”; if (y>temp) temp=y; if(z>temp) temp=z; return temp; } CS3369 Real Time Control Software/DENG Xiaotie

  17. Question 9. What are the outputs of the following program? #include<iostream.h> int computation(int x); void main() { int z, w, w1,x=10; /* x he is a variable that can be used in main() */ z=computation(5); w=computation(z); w1=computation(x); cout<<z<<w<<w1 } int computation(int x) /*x here is a formal parameter */ { int y; y=x*x+25; cout<<“input is”<<x<<“\n”; return y; } CS3369 Real Time Control Software/DENG Xiaotie

  18. Question 10. What are the outputs of the following program? #include<iostream.h> int x, int y, int z; int max (); void main() { int temp_max; x=90; y=91; z=92; cout<<z<<“\n”; temp_max=max(); cout<<“The maximum is”; cout << temp_max; cout<<z; } int max () { int temp=x; cout<<“The input numbers are”; cout <<x<<y<<z<<“\n”; if (y>temp) temp=y; if(z>temp) temp=z; z=z+1; return temp; } CS3369 Real Time Control Software/DENG Xiaotie

  19. Question 11. (Moderate) Write a function that takes three integers as its input parameters and outputs the smallest number among the three integers. The prototype of the function is as follows: int minmum(int x, int y, int z); Question 12. (Hard) Write a program that (1) asks the user to input an integer from the screen, (2) the input integer should be in the range [0, 100] or [200, 300], and (3) if the input integer is not in the required ranges, ask the user to re-enter the integer until the integer is in the required ranges. CS3369 Real Time Control Software/DENG Xiaotie

More Related