Question
Answer and Explanation
In the C programming language, the scanf function can parse numbers represented in scientific notation using the format specifier %e, %E, or %f. When dealing with scientific notation, scanf interprets digits in a specific way:
1. General Format:
- Scientific notation typically follows the format: mE±n or mE±n, where:
- m is the mantissa (a decimal number, which can include a decimal point).
- E or e indicates the exponent part.
- ± is the sign of the exponent (either + or -).
- n is the integer exponent.
2. Mantissa Digits:
- The mantissa (m) can include any number of digits before and after the decimal point. scanf will read these digits as part of the floating-point number.
- Examples of valid mantissas: 1.23, -456, 0.007, 12345.
3. Exponent Digits:
- The exponent (n) is an integer value that follows the E or e. It can be positive or negative.
- scanf expects at least one digit for the exponent. Leading zeros are allowed, but not required.
- Examples of valid exponents: +2, -3, 0, 10, -05.
4. Sign Handling:
- The mantissa can optionally start with a + or - sign. If no sign is present, it's assumed to be positive.
- The exponent must have a sign (+ or -) or no sign, in which case it is assumed to be positive.
5. Examples of Valid Scientific Notation Inputs for scanf:
- 1.23e+4
- -4.56E-2
- 7e0
- 0.008e-5
- 12345E+10
6. Using scanf:
- To read a floating-point number in scientific notation, you can use %e, %E, or %f. All three will handle scientific notation.
- Example:
#include <stdio.h>
int main() {
float num;
printf("Enter a number in scientific notation: ");
scanf("%e", &num);
printf("You entered: %f\\n", num);
return 0;
}
In summary, scanf parses scientific notation by reading the mantissa (including decimal digits), the exponent indicator (E or e), and the exponent (including its sign and digits). It's flexible in terms of the number of digits in the mantissa and exponent, but it requires at least one digit for the exponent.