Programming Final

• Reasons to learn C


  • Understand how a computer works (memory management and allocation)
  • C is the fundamental language for all other languages (Python and Java can interface with C programming. Also easier to learn other programming languages)
  • Opportunity to work on open source projects
• How to print "Hello World" in C

  1. #include<stdio.h>

  2. int main(){

  3. printf("Hello, World!\n");

  4. return 0;

  5. }
• How to compile a C source code

  gcc -o helloWorld helloWorld.c
• stdio.h


  The header file in your C program. Needed to access the libraries required to run the code. Provides access to functions like printf.
• Program to take integer input from user and print it back


  1. #include <stdio.h>

  2. int main()

  3. {

  4. int testInteger;

  5. printf("Enter an integer: ");

  6. scanf("%d",&testInteger);

  7. printf("Number = %d",testInteger);

  8. return 0;

  9. }
• Program to take string input from user and print it back


  1. #include<stdio.h>

  2. int main()

  3. {

  4. char str[100];

  5. printf("Please type a word:\n");

  6. gets(str);

  7. puts("You entered: ");

  8. puts(str);

  9. return 0;

  10. }
• Program to take two integers from user and print their sum


  1. #include <stdio.h>

  2. int main()

  3. {

  4. int a, b, c;

  5. printf("Enter the first value: ");

  6. scanf("%d", &a);

  7. printf("Enter the second value: ");

  8. scanf("%d",&b);

  9. c = a+b;

  10. printf("%d +%d = %d\n", a, b, c);

  11. return 0;

  12. }
• C compilers in macOS and Windows

  • macOS: clang
  • Windows: mingw
• Format string and &variable in scanf()

  • Format string - specifies the format of the input
  • &variable - pointer to the variable to store the input value
• scanf("%[^\n]", str_array) and getchar()

  • %[^\n] scans for a string until a newline character
  • getchar() reads the newline character left in the buffer after scanf()
• EOF

  End-of-file signal sent to indicate the end of a file
• Function prototype

  Declaration of a function before its definition
• Pointer in C

  A variable that holds the address of another variable
• &, *


  • & gives the address of an object
  • * is the indirection/dereferencing operator to access the object a pointer points to
• Program to add two user-given numbers using pointers

  1. #include <stdio.h>

  2. int main()

  3. {

  4. int num1, num2, sum;

  5. int *ptr1, *ptr2;

  6. ptr1 = &num1;

  7. ptr2 = &num2;

  8. printf("Enter any two numbers: ");

  9. scanf("%d%d", ptr1, ptr2);

  10. sum = *ptr1 + *ptr2;

  11. printf("Sum = %d", sum);

  12. return 0;

  13. }
• scanf() doesn't need & on char[] (strings)