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1. Data types, Type Conversion Session No. 10 Course Name: Programming for Problem Solving Course Code: E1UA102C Instructor Name: Duration: 50 min Date of Conduction of Class:03/10/2025 Galgotias Student-Centered Active Learning Ecosystem 1

2. Galgotias Student-Centered Active Learning Ecosystem 2 Difference between variable and constants. RECAP #include < stdio.h > int main() { const int DAYS_IN_WEEK = 7; int days = 5; printf ("Days: %d", days); days = 10; // valid printf ("Updated Days: %d\n", days); return 0; }

3. Galgotias Student-Centered Active Learning Ecosystem 3 Opening If you had to store your age, your height in meters, and the first letter of your name in C — which data types would you choose? What happens if you add an int and a float ? Can a double fit into an int ? What might happen?

4. At the end of this session you will be able to LO1: Identify and use appropriate C datatypes (int, float, char, etc.) for storing and manipulating different kinds of data effectively. LO2: : A pply implicit and explicit type conversions (casting) in C to ensure accurate data handling and computation. 4

5. Outline Data types in C Basic data type Derived data type User-defined data type Type casting 5

6. In C programming , data types define the type of data a variable can hold and how much memory it will occupy . 6 DATA TYPE IN C

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8. 8 BASIC DATA TYPE IN C Data Type Size (depends on system, typically 32-bit/64-bit) Description Format Specifier int 2 or 4 bytes Stores integers (whole numbers). %d float 4 bytes Stores single-precision decimal numbers. %f double 8 bytes Stores double-precision decimal numbers. % lf char 1 byte Stores a single character or small integer. %c Void — Represents no value / empty type. bool 1 byte Represents two values : true (1) and false (0). Use #include < stdbool.h > %d

9. 9 BASIC DATA TYPE IN C #include < stdio.h > // Function with void return type void showMessage () { printf ("This is a function with void return type.\n\n"); } int main() { // Basic data types int age = 25; // Integer float height = 5.9f; // Floating point double salary = 55000.75; // Double precision char grade = 'A'; // Character // Printing values printf ("Values of Basic Data Types:\n"); printf ("Integer (age) : %d\n", age); printf ("Float (height) : %.2f\n", height); printf ("Double (salary) : %.2lf\n", salary); printf ("Char (grade) : %c\n\n", grade); // Printing sizes printf ("Sizes of Basic Data Types:\n"); printf ("Size of int : % zu bytes\n", sizeof (int)); printf ("Size of float : % zu bytes\n", sizeof (float)); printf ("Size of double : % zu bytes\n", sizeof (double)); printf ("Size of char : % zu bytes\n", sizeof (char)); printf ("Size of void : N/A (no storage)\n"); // Call void function showMessage (); return 0; }

10. 10 BASIC DATA TYPE IN C #include < stdio.h > #include < stdbool.h > // Required for bool, true, false int main() { bool isEven = true; bool isOdd = false; if ( isEven ) { printf ("The number is even.\n"); } if (! isOdd ) { printf ("The number is not odd.\n"); } return 0; }

11. 11 MODIFIERS TO BASIC DATA TYPE IN C C provides modifiers to alter the size and range of basic data types: short , long , signed, unsigned Type Typical Size Range short int 2 bytes -32,768 to 32,767 unsigned short int 2 bytes 0 to 65,535 long int 4 bytes -2,147,483,648 to 2,147,483,647 unsigned long int 4 bytes 0 to 4,294,967,295 long long int 8 bytes Very large range unsigned long long int 8 bytes Only positive values

12. 12 BASIC DATA TYPE IN C Format Specifiers in C (with Modifiers) 🔹 Integer Types Data Type Format Specifier (printf) Example int %d or %i printf("%d", a); short int / short %hd printf("%hd", s); unsigned short int %hu printf("%hu", us); unsigned int %u printf("%u", u); long int / long %ld printf("%ld", l); unsigned long int % lu printf("%lu", ul); long long int %lld printf("%lld", ll); unsigned long long int %llu printf ("% llu ", ull );

13. 13 BASIC DATA TYPE IN C Format Specifiers in C (with Modifiers) 🔹 Character Types Data Type Format Specifier Example char %c printf("%c", ch); signed char %c printf("%c", sch); unsigned char %c (but prints as integer if %d) printf ("%d", uch ); 🔹 Floating-Point Types Data Type Format Specifier Example float %f printf("%f", f); double %lf printf("%lf", d); long double %Lf printf ("% Lf ", ld );

14. 14 DERIVED DATA TYPE IN C These are derived from the basic types: Arrays → collection of similar data types (int arr [10]). Pointers → store the address of a variable (int *p). Functions → return values and take arguments of specific types.

15. 15 DERIVED DATA TYPE IN C Derived Data Type Description Syntax Example Notes Array Collection of elements of the same type , stored in contiguous memory . datatype arrayName [size]; int marks[5]; Index starts at 0. Size must be constant (in C89), but C99 allows variable-length arrays. Pointer Variable that stores the address of another variable . datatype *pointerName; int *ptr; Powerful but error-prone; can be used for dynamic memory, arrays, and function references. Function Block of code that performs a specific task and can return a value . returnType functionName(parameters); int add(int a, int b); Functions themselves are first-class citizens; function pointers allow passing functions as arguments.

16. 16 USER DEFINED DATA TYPE IN C C allows creating custom data types using: Structures (struct) → group of different data types. Unions (union) → similar to structures, but shares memory. enum → Used to assign names to integer constants, improving readability . typedef → gives a new name to an existing type.

17. 17 USER DEFINED DATA TYPE IN C User-Defined Type Description Syntax Example Notes struct (Structure) Groups variables of different data types under one name. struct tag { datatype member1; datatype member2; ... }; c struct Student { int id; char name[20]; }; Members stored separately , each has its own memory. Access using dot (.). union Similar to struct, but members share the same memory location . union tag { datatype member1; datatype member2; ... }; c union Data { int i; float f; char c; }; Memory efficient . Only one member active at a time (size = largest member). enum (Enumeration) Defines a set of named integer constants . enum tag { CONST1, CONST2, ... }; c enum Days { MON, TUE, WED, THU, FRI, SAT, SUN }; By default, values start from 0. Can assign custom values. typedef Provides a new name (alias) for an existing data type. typedef existingType newName; c typedef unsigned int uint; uint x = 10; Improves readability and portability. Commonly used with struct, enum .

18. ACTIVITY 1 : Problem Based Learning Sort them into categories: Basic, Derived, User-defined, Enumeration. int marks; float temperature; char grade; double salary; int arr [10]; struct student { int id; char name[20]; }; typedef unsigned int uint ; enum days { MON, TUE, WED, THU, FRI, SAT, SUN };

19. ACTIVITY 2 : Problem Based Learning “Fix the Code” Challenge #include < stdio.h > int main() { char age = 25; float grade = 'A’; int name = "Alice"; double salary = 5000.75; printf ("%d %f %s % lf ", age, grade, name, salary); return 0; } Task: Identify errors and suggest correct data types and format specifiers .

20. 20 TYPE CONVERSION IN C Type conversion in C is the process of converting a value of one data type into another. It allows you to perform operations between different types of data. There are two main types of type conversion in C: implicit (automatic) conversion and explicit (manual) conversion .

21. 21 TYPE CONVERSION IN C 1. Implicit Type Conversion (Type Casting / Type Promotion) This is done automatically by the compiler when different data types are used in an expression. C promotes the smaller or lower-ranked data type to a higher-ranked type to avoid loss of information. Rules of implicit conversion (usual arithmetic conversions): char → int short → int int → float → double float → double

22. 22 TYPE CONVERSION IN C #include < stdio.h > int main() { int a = 5; float b = 2.5; float c; c = a + b; // 'a' is automatically converted to float printf ("%f\n", c); // Output: 7.500000 return 0; }

23. 23 TYPE CONVERSION IN C 2. Explicit Type Conversion (Type Casting) This is when the programmer manually converts a variable from one type to another using type cast operator: (type) . Syntax: (type) expression

24. 24 TYPE CONVERSION IN C #include < stdio.h > int main() { float a = 9.7; int b; b = (int)a; // explicit conversion from float to int printf ("%d\n", b); // Output: 9 return 0; } Example of Explicit Type Conversion (Type Casting) Here, (int)a explicitly converts the float 9.7 to the integer 9 by truncating the decimal part.

25. 25 TYPE CONVERSION IN C Quick Rules to Remember Implicit conversion : Happens automatically in expressions; smaller types are promoted to larger types (char → int, int → float). Explicit conversion (casting): Programmer specifies the target type using (type). Precision loss occurs when converting from float/double → int. Overflow/underflow can happen when converting between types with different ranges (int → char or signed ↔ unsigned).

26. 26 Comprehensive table of type conversions in C CCONVERSION IN C From Type To Type Conversion Type Example Notes int float Implicit/Explicit float f = 10; f = (float)10; Integer converted to float automatically or manually. float int Explicit int i = (int)3.9; Decimal part is truncated. char int Implicit/Explicit char c = 'A'; int i = c; 'A' becomes 65 (ASCII). int char Explicit char c = (char)65; ASCII value converted to character. double float Explicit float f = (float)3.14159; Precision may be lost. float double Implicit double d = 2.5f; Float promoted to double automatically. short int Implicit short s = 10; int i = s; Small integer promoted to int. int short Explicit short s = (short)1000; May cause overflow if value too large. unsigned int int Implicit/Explicit unsigned int u = 300; int i = (int)u; Watch out for negative values if overflow occurs. int unsigned int Explicit unsigned int u = (unsigned int)(-1); Converts negative number to large positive.

27. Activity #include < stdio.h > int main() { int a = 5; float b = 2.0; double c = 3.5; // Example 1: Implicit conversion float result1 = a + b; // Example 2: Explicit conversion int result2 = (int)c + a; printf ("result1 = %f\n", result1); printf ("result2 = %d\n", result2); return 0; } Task: Predict the output of result1 and result2. 2. Identify where implicit and explicit conversions occur.

28. Summary In C programming, data types define the type of data a variable can hold and how much memory it will occupy. Type conversion in C is the process of converting a value of one data type into another. It allows you to perform operations between different types of data. There are two main types of type conversion in C: implicit (automatic) conversion and explicit (manual) conversion.

29. LO1: Identify and use appropriate C datatypes (int, float, char, etc.) for storing and manipulating different kinds of data effectively. LO2: : A pply implicit and explicit type conversions (casting) in C to ensure accurate data handling and computation. 29 Attainment of LOs in alignment to the learning

30. Discussion on the post session activity Attempt the Post-session activity on LMS, before next session

31. Information to next topic of the course Next session: Operators and expressions

32. Review and Reflection from students