Why Does `pow(10, 5)` Sometimes Return 9999 Instead of 10000 in C ?

Why pow(10,5) Displays 9,999 Instead of 10,000 in C

In C , when using the pow() function with integer inputs and floating-point exponents, unexpected results can occur due to the representation of floating-point values. Specifically, pow(10.0, 5) may result in a value of 9999.9999999 or similar. When this floating-point value is assigned to an integer variable, it is truncated.

For instance, consider the following code snippet:

const int sections = 10;

for(int t = 0; t < 5; t++){
   int i = pow(sections, 5- t -1);  // <-- pow() with integer base, floating-point exponent
   cout << i << endl;
}

The output of this code will incorrectly display:

9999
1000
99
10
1

However, if the code is modified to use the pow() function directly in the cout statement, the expected results are obtained:

for(int t = 0; t < 5; t++){
    cout << pow(sections,5-t-1) << endl; // <-- pow() used directly in cout
}

With this modification, the output will correctly display:

10000
1000
100
10
1

This discrepancy occurs because in the first example, the floating-point result of pow(sections, 5- t -1) is truncated when assigned to an integer variable. In the second example, however, the floating-point result is rounded when passed directly to cout, resulting in the correct display.

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