CSC231 Powers of 2 in C++
(Redirected from CSC231 C++ Program and infinite loops)
--D. Thiebaut 13:43, 8 October 2010 (UTC)
This exercise is a companion of the same exercise dealing with a Python implementation of the program.
Exercise
- Below is a C++ program, and its complete output
- Question 1
- Do the numbers output by the program look correct?
- Question 2
- Remove the comment sign (//) in front of the last printf. Compile and run the program again.
- Explain the new output!
- Question 3
- Remove the word unsigned from the program. This changes the integer variable from an unsigned variable to a signed one.
- Change the %u printing format command by %d to indicate that you want to print the contents of a signed variable.
- Predict the output of the program.
- Verify whether you were correct in your prediction!
The C++ Program
// mulby2.cpp
// D. Thiebaut
// To compile and run:
//
// g++ -o mulby2 mulby2.cpp
// ./mulby2
//
#include <stdio.h>
int main() {
unsigned int x = 1;
for ( int i=0; i<32; i++ ) {
printf ( "%u\n", x );
x = x * 2;
}
//printf( "final x = %u\n\n", x );
return 0;
}
The Output
g++ -o mulby2 mulby2.cpp
./mulby2
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
16777216
33554432
67108864
134217728
268435456
536870912
1073741824
2147483648