17. Scientific Notation Output

📝 Problem

Accept a float value as input and print the same in its exponential form.

Input Format:
Read a Float number

Output Format:
Exponential form of the float value

Constraints:
2.3E-308 <=N< =1.7E+308

🔬 Understanding Scientific Notation

What is Scientific Notation?

Scientific notation (also called exponential notation) is a way to express very large or very small numbers in a compact format using powers of 10.

Format Breakdown:

1.234567e+03

Mantissa:

1.234567 (the significant digits)

Exponent:

+03 (power of 10)

Meaning:

1.234567 × 10³ = 1234.567

🎯 The `scientific` Manipulator

In C++, the scientific manipulator from <iomanip> forces output to use exponential notation.

                            Key Point: scientific is the opposite of fixed!
                            fixed → Regular decimal notation (1234.567)
scientific → Exponential notation (1.234567e+03)

                        

📊 Comparison: fixed vs scientific

Original Number	fixed	scientific
`1234.567`	`1234.567000`	`1.234567e+03`
`0.00123`	`0.001230`	`1.230000e-03`
`5000000`	`5000000.000000`	`5.000000e+06`
`0.0000007`	`0.000001`	`7.000000e-07`

💡 When to Use Scientific Notation?

✅ Astronomy: Distance to stars (9.461e+15 meters)
✅ Physics: Avogadro's number (6.022e+23)
✅ Chemistry: Atomic masses (1.67e-27 kg)
✅ Engineering: Micro/nano measurements (5.2e-09 meters)
✅ Computing: Very large/small calculations

🔧 Combining with `setprecision()`

You can control the precision of the mantissa:

cout << scientific << setprecision(3) << 1234.567;
// Output: 1.235e+03 (3 digits after decimal)

⚙️ Default Behavior

By default, scientific shows 6 decimal places in the mantissa
Always shows sign of exponent (+ or -)
Exponent is at least 2 digits (e+03 not e+3)
The mantissa is always normalized: 1.0 ≤ mantissa < 10.0

🔄 Reverting to Default

To go back to default formatting (auto-selection of fixed/scientific):

cout << defaultfloat;  // Resets to default behavior

                            Remember: scientific is persistent - it stays active for all 
                            subsequent outputs until you change it with fixed or defaultfloat.
                        

📚 Related Questions:

Examples

Sample Input 1:

Input:

1234.567

Sample Output 1:

Output:

1.234567e+03

Meaning: 1.234567 × 10³ = 1234.567

More Examples:

Input: 0.00567

Output: 5.670000e-03

Input: 9500000

Output: 9.500000e+06

Input: 0.0000042

Output: 4.200000e-06

Solution.cpp

#include <iostream>
#include <iomanip>

using namespace std;

int main() {
    long double f;
    cin >> f;
    
    // scientific: Forces exponential notation
    // Format: [mantissa]e[+/-][exponent]
    // Example: 1234.567 → 1.234567e+03
    cout << scientific << f;
    
    return 0;
}