OBJECTIVE: You need practice in manipulating C-strings (and arrays in general) plus using command-line arguments (i.e., using the argc/argv mechanism).

TASK: Write a C++ program that will add two or more binary numbers. These binary numbers appear as command-line arguments. The resulting sum is output to standard output (stdout). You may assume only well-formed (valid) binary numbers will be entered as command-line arguments. Design your program as a command. It should take two or more binary numbers following the command on the command line as input and output their binary sum. For example, executing the following command line binadd 101 1100 should result in a value of 10001 being output. Similarly, executing the following binadd 100 1 1101 0 should print 10010 . The format of the binary sum should be a left-justified, left-zero-suppressed binary value; do not produce any output except the binary sum. In the event of an overflow or other error, simply print the letter 'E' as output.

IMPLEMENTATION NOTES: Define a function with three parameters, called Badd, which adds, digit by digit, the binary numbers represented by the first two string arguments and deposits the sum in the third argument; the function prototype is

 bool Badd( const char augend[], const char addend[], char sum[] ); // IN IN OUT 

Use the Badd function to perform the binary number additions. The Badd function returns true on successful addition and false otherwise. Use symbolic constants to declare the size of all arrays, loop iterations, and other maximum sizes so that the program can be expanded to handle various size binary numbers by changing the constant values and recompiling. The symbol that controls the maximum length of the binary number's sum is called MAX_DIGITS. The value MAX_DIGITS may be as low as 2; there is no upper-bound (although in practice this value will be 256 or less). Compile and test a 5-digit version of your program. (You will not be submitting any execution results from the 5-digit version.) Then compile and demonstrate a 36-digit version of your program. The source version that you hand in must have MAX_DIGITS = 36.

Use only one source file for this program (i.e., do not use external functions). Use as your source file name "binadd.cpp". A stubbed starter skeleton program is available as$PUB/binaddStart.cpp. Copy this file over as binadd.cpp and add your code and changes to it. Do not modify the main routine or the Badd function prototype; your task is to implement the Badd function.

binaddStart.cpp

// For example: binadd 100 1 1101 0 // should print 10010 // // . 1 . 2 . 3 . 4 . 5 . 6 . 7 . //3456789012345678901234567890123456789012345678901234567890123456789012345 #include  #include  using namespace std; const int MAX_DIGITS = 36; // Maximum digits in (output) sum bool Badd( const char augend[], const char addend[], char sum[] ); // IN IN OUT int main( int argc, char* argv[] ) // IN IN { char partialSum[MAX_DIGITS+1]; // Partial sum of the binary numbers char sum[MAX_DIGITS+1]; // Sum of the binary numbers bool noError; // No error flag // Exit if insufficient arguments were supplied. if (argc < 3) { cout << "Error: insufficient arguments. "; return 1; } // Add together the first two binary numbers on the command-line. noError = Badd( argv[1], argv[2], sum ); // Add any additional binary numbers to the partial sum. for (int counter = 3; noError && counter < argc; counter++) { strcpy( partialSum, sum ); noError = Badd( partialSum, argv[counter], sum ); } // Print answer on standard output. if (noError) cout << sum << endl; else cout << 'E' << endl; return 0; } // end main bool Badd( const char augend[], const char addend[], char sum[] ) // IN IN OUT // Pre: augend and addend are strings representing valid binary numbers. // Post: sum is a string representing the sum of augend + addend. // Returns true if successful in addition, false otherwise. { // Temporary stub code. Return a string representing binary zero. sum[0] = '0'; sum[1] = '\0'; return true; } // end Badd