Decimal to Binary
Repeated division by two produces binary digits from least significant to most significant.
What is Decimal to Binary?
Repeated division by two produces binary digits from least significant to most significant.
Convert a positive decimal integer to binary.
Important points
- Compile with warnings enabled and fix every warning.
- Know the lifetime and type of every value.
- Validate input and keep array bounds explicit.
C and C++ code examples
main.c
#include <stdio.h>
int main(void) {
unsigned number = 13, value = number; int bits[32], count = 0;
// Store remainders generated from right to left.
do { bits[count++] = value % 2; value /= 2; } while (value);
printf("%u = ", number); while (count) printf("%d", bits[--count]); puts("");
}
13 = 1101C++
main.cpp
#include <bitset>
#include <iostream>
#include <string>
int main() {
unsigned number = 13;
// Remove leading zeroes from a fixed-width bitset string.
std::string bits = std::bitset<32>(number).to_string();
bits.erase(0, bits.find_first_not_of('0'));
std::cout << number << " = " << bits << '\n';
}
13 = 1101C and C++ comparison
Store remainders and print them in reverse order because division discovers the final digit first.
C
C exposes small procedural APIs and makes representation details explicit.
C++
C++ retains the low-level model while adding safer library types and abstractions.
Practice exercises
Run both versions, then modify them to observe the different language guarantees.
- Add invalid and boundary-value inputs.
- Compile with -Wall -Wextra -Wpedantic.
- Move reusable declarations into a header and implementation file.