AP Computer Science a Flashcards: Casting And Range Of Variables

What this deck covers

This deck focuses on Casting And Range Of Variables, giving you a quick way to review the definitions, rules, and examples that matter most for AP Computer Science a.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Identify the cast needed to convert byte to short.

Answer: Implicit cast: No cast needed. Widening from 8-bit to 16-bit integer.

Flashcard 2: Identify the cast needed to convert double to float.

Answer: Explicit cast: (float) value. Narrowing conversion loses precision.

Flashcard 3: What is overflow in the context of variable casting?

Answer: Overflow is exceeding the maximum range of a data type. Value wraps around when exceeding maximum.

Flashcard 4: What happens when casting float to int?

Answer: The fractional part is truncated. Decimal portion removed, not rounded.

Flashcard 5: What happens if you cast a double to int?

Answer: Fractional part is truncated. Decimal portion discarded, integer part kept.

Flashcard 6: What is the default data type for decimal values in Java?

Answer: double. Java infers double for literal decimal values.

Flashcard 7: What is the result of casting char to int?

Answer: The Unicode value of the character. char represents Unicode code points.

Flashcard 8: Identify the cast needed to convert double to int.

Answer: Explicit cast: (int) value. Narrowing conversion requires explicit cast operator.

Flashcard 9: What is the default data type for decimal values in Java?

Answer: double. Java infers double for literal decimal values.

Flashcard 10: What is a widening conversion?

Answer: Converting a smaller data type to a larger one. Preserves data when increasing capacity.

Flashcard 11: What is a narrowing conversion?

Answer: Converting a larger data type to a smaller one. Potential data loss when reducing precision.

Flashcard 12: How do you cast an int to a double?

Answer: Implicit cast: No cast needed. Widening conversion happens automatically.

Flashcard 13: What is underflow in the context of variable casting?

Answer: Underflow is exceeding the minimum range of a data type. Value wraps around when below minimum.

Flashcard 14: Can you cast boolean to int in Java?

Answer: No, boolean cannot be cast to int. boolean is incompatible with numeric types.

Flashcard 15: What is a narrowing conversion?

Answer: Converting a larger data type to a smaller one. Potential data loss when reducing precision.

Flashcard 16: What is casting in Java?

Answer: Casting is converting a variable from one data type to another. Required when changing between incompatible types.

Flashcard 17: Identify the cast needed to convert char to byte.

Answer: Explicit cast: (byte) value. Narrowing from 16-bit to 8-bit integer.

Flashcard 18: Find the cast needed to convert long to int.

Answer: Explicit cast: (int) value. Narrowing conversion from 64-bit to 32-bit.

Flashcard 19: What are primitive data types in Java?

Answer: byte, short, int, long, float, double, char, boolean. Eight basic data types built into Java.

Flashcard 20: What is the range of a float in Java?

Answer: Approximately $3.4 \times 10^{-38}$ to $3.4 \times 10^{38}$. 32-bit IEEE 754 floating-point precision.

Flashcard 21: What is implicit casting?

Answer: Implicit casting is automatic type conversion by the Java compiler. Happens when widening conversions are safe.

Flashcard 22: What is the effect of casting int to char?

Answer: Character representation of the int value. Unicode value converted to character symbol.

Flashcard 23: What is the range of a long in Java?

Answer: $-2^{63}$ to $2^{63}-1$. Standard 64-bit signed integer range.

Flashcard 24: What is the effect of casting int to char?

Answer: Character representation of the int value. Unicode value converted to character symbol.

Flashcard 25: Which cast should be used to convert float to double?

Answer: Implicit cast: No cast needed. Widening conversion preserves precision.

Flashcard 26: Identify the cast needed to convert double to int.

Answer: Explicit cast: (int) value. Narrowing conversion requires explicit cast operator.

Flashcard 27: What is a widening conversion?

Answer: Converting a smaller data type to a larger one. Preserves data when increasing capacity.

Flashcard 28: What is the range of a byte in Java?

Answer: $-2^{7}$ to $2^{7}-1$. Standard 8-bit signed integer range.

Flashcard 29: Can you implicitly cast int to float?

Answer: Yes, int can be implicitly cast to float. int fits within float's range safely.

Flashcard 30: Which data type is used for precise decimal values?

Answer: double. double provides highest precision for decimals.

Flashcard 31: What is the range of a byte in Java?

Answer: $-2^{7}$ to $2^{7}-1$. Standard 8-bit signed integer range.

Flashcard 32: Find the cast needed to convert long to int.

Answer: Explicit cast: (int) value. Narrowing conversion from 64-bit to 32-bit.

Flashcard 33: What keyword is used to explicitly cast types?

Answer: Cast operator, e.g., (int) or (float). Parentheses with target type name.

Flashcard 34: What is the range of a char in Java?

Answer: $0$ to $65535$ (unsigned). 16-bit Unicode characters from 0 to 65535.

Flashcard 35: What is implicit casting?

Answer: Implicit casting is automatic type conversion by the Java compiler. Happens when widening conversions are safe.

Flashcard 36: What is type promotion in expressions?

Answer: Automatic conversion of types to prevent data loss. Smaller types promoted to avoid overflow.

Flashcard 37: How would you cast int to byte?

Answer: Explicit cast: (byte) value. Narrowing conversion from 32-bit to 8-bit.

Flashcard 38: Can you implicitly cast int to float?

Answer: Yes, int can be implicitly cast to float. int fits within float's range safely.

Flashcard 39: Can you cast boolean to int in Java?

Answer: No, boolean cannot be cast to int. boolean is incompatible with numeric types.

Flashcard 40: What is the result of casting int to boolean?

Answer: Not allowed; compile-time error. boolean and numeric types are incompatible.

Flashcard 41: Which data type is used for precise decimal values?

Answer: double. double provides highest precision for decimals.

Flashcard 42: What is a potential issue when casting long to int?

Answer: Loss of data if the value exceeds int range. Values outside int range cause overflow.

Flashcard 43: How would you cast int to byte?

Answer: Explicit cast: (byte) value. Narrowing conversion from 32-bit to 8-bit.

Flashcard 44: Identify the cast needed to convert double to float.

Answer: Explicit cast: (float) value. Narrowing conversion loses precision.

Flashcard 45: What is a potential issue when casting long to int?

Answer: Loss of data if the value exceeds int range. Values outside int range cause overflow.

Flashcard 46: What is the result of casting char to int?

Answer: The Unicode value of the character. char represents Unicode code points.

Flashcard 47: What is casting in Java?

Answer: Casting is converting a variable from one data type to another. Required when changing between incompatible types.

Flashcard 48: What is the purpose of casting in programming?

Answer: To convert one data type to another. Ensures compatibility between different data types.

Flashcard 49: What are primitive data types in Java?

Answer: byte, short, int, long, float, double, char, boolean. Eight basic data types built into Java.

Flashcard 50: What is explicit casting?

Answer: Explicit casting is manually converting a data type using a cast operator. Required for narrowing conversions to prevent data loss.

Flashcard 51: Which data type has the largest range: int, short, or byte?

Answer: int. int has 32 bits vs 16 for short, 8 for byte.

Flashcard 52: What is the range of a float in Java?

Answer: Approximately $3.4 \times 10^{-38}$ to $3.4 \times 10^{38}$. 32-bit IEEE 754 floating-point precision.

Flashcard 53: What is the range of a double in Java?

Answer: Approximately $1.7 \times 10^{-308}$ to $1.7 \times 10^{308}$. 64-bit IEEE 754 floating-point precision.

Flashcard 54: Identify the cast needed to convert short to long.

Answer: Implicit cast: No cast needed. Widening from 16-bit to 64-bit integer.

Flashcard 55: What is type promotion in expressions?

Answer: Automatic conversion of types to prevent data loss. Smaller types promoted to avoid overflow.

Flashcard 56: What is underflow in the context of variable casting?

Answer: Underflow is exceeding the minimum range of a data type. Value wraps around when below minimum.

Flashcard 57: Identify the cast needed to convert short to long.

Answer: Implicit cast: No cast needed. Widening from 16-bit to 64-bit integer.

Flashcard 58: What is the range of a char in Java?

Answer: $0$ to $65535$ (unsigned). 16-bit Unicode characters from 0 to 65535.

Flashcard 59: What happens when casting float to int?

Answer: The fractional part is truncated. Decimal portion removed, not rounded.

Flashcard 60: What is the purpose of casting in programming?

Answer: To convert one data type to another. Ensures compatibility between different data types.

Flashcard 61: What is overflow in the context of variable casting?

Answer: Overflow is exceeding the maximum range of a data type. Value wraps around when exceeding maximum.

Flashcard 62: What is the range of a short in Java?

Answer: $-2^{15}$ to $2^{15}-1$. Standard 16-bit signed integer range.

Flashcard 63: What is the range of a short in Java?

Answer: $-2^{15}$ to $2^{15}-1$. Standard 16-bit signed integer range.

Flashcard 64: What is the range of an int in Java?

Answer: $-2^{31}$ to $2^{31}-1$. Standard 32-bit signed integer range.

Flashcard 65: Which cast should be used to convert float to double?

Answer: Implicit cast: No cast needed. Widening conversion preserves precision.

Flashcard 66: Identify the cast needed to convert byte to short.

Answer: Implicit cast: No cast needed. Widening from 8-bit to 16-bit integer.

Flashcard 67: Which data type has the largest range: int, short, or byte?

Answer: int. int has 32 bits vs 16 for short, 8 for byte.

Flashcard 68: What is the range of a double in Java?

Answer: Approximately $1.7 \times 10^{-308}$ to $1.7 \times 10^{308}$. 64-bit IEEE 754 floating-point precision.

Flashcard 69: What is explicit casting?

Answer: Explicit casting is manually converting a data type using a cast operator. Required for narrowing conversions to prevent data loss.

Flashcard 70: What happens if you cast a double to int?

Answer: Fractional part is truncated. Decimal portion discarded, integer part kept.

Flashcard 71: What is the result of casting int to boolean?

Answer: Not allowed; compile-time error. boolean and numeric types are incompatible.

Flashcard 72: What happens when you cast a larger type to a smaller type?

Answer: Possible data loss or precision loss. Narrowing conversions truncate or overflow values.

Flashcard 73: How do you cast an int to a double?

Answer: Implicit cast: No cast needed. Widening conversion happens automatically.

Flashcard 74: What is the range of a long in Java?

Answer: $-2^{63}$ to $2^{63}-1$. Standard 64-bit signed integer range.

Flashcard 75: What is the range of an int in Java?

Answer: $-2^{31}$ to $2^{31}-1$. Standard 32-bit signed integer range.

Flashcard 76: What happens when you cast a larger type to a smaller type?

Answer: Possible data loss or precision loss. Narrowing conversions truncate or overflow values.

Flashcard 77: What keyword is used to explicitly cast types?

Answer: Cast operator, e.g., (int) or (float). Parentheses with target type name.

Flashcard 78: Identify the cast needed to convert char to byte.

Answer: Explicit cast: (byte) value. Narrowing from 16-bit to 8-bit integer.