Question

Write the code in C language.

Computer communication networks sometimes have noise on them, which can corrupt data being transmitted. It is the responsibility of the computers communicating to confirm data is transmitted accurately. One method to do this is to calculate a checksum of the data and transmit the checksum along with the data to ensure accuracy. In C, we can compute a checksum simply by summing the integer ASCII codes in the message and finding the remainder of this sum divided by 64. For example, consider the message "ABC". To compute the checksum, add 65+66+67 to get 198, then divide by 64 to get a remainder of 6, which is used as your checksum. Now, when the data is transmitted, both the sending and receiving computers can compute a checksum and confirm the data was transmitted precisely.

1. Start by writing the function

int generate_checksum( char c, int so_far );

The parameter c is a character to be added to the checksum. The parameter so_far is the value calculated and returned by previous calls to the generate_checksum( ) function. It will have to be a zero the first time you invoke it. Write a driver function to test your function with a few characters, confirming it is returning the appropriate answers.

Added 'A': generate_checksum returned 1.

Added 'B': generate_checksum returned 3.

Added 'C': generate_checksum returned 6.

Your driver is going to have to make repeated calls to the generate_checksum( ) function, along the lines of:

so_far = generate_checksum( 'A', 0 );

so_far = generate_checksum( 'B', so_far );

so_far = generate_checksum( 'C', so_far );

Each call feeds back in the value calculated in the previous call. Obviously, you can use an appropriate iterator to simply your driver code. Make sure you include the driver when submitting this assignment.

2. Step two, write the function

get_string_and_checksum( )

using an iterator that continues to read in characters from the keyboard until the user enters a period.

Use the C standard

getchar( )

function to read in the individual characters. Each call to this function returns a single character from the keyboard.

After each character is read in, invoke your function generate_checksum ( ) to calculate the current checksum. Your function should not output anything until the user enters a line with a period on it.

When the user enters a period at the end, display the checksum and then prompt for the next string.

Your program should continue prompting for a string until the user enters a line with only a period on it. Common error: Make sure you do not add the period to the checksum

Answer 1

Here is the Code: (with comments explaining the logic)

Here is the same code: (Without comments, for better readability)

Here is the code(In plain-text format, in order to copy-paste into your compiler)

 #include <stdio.h> int generate_checksum(char c, int so_far) { int Ascii = (int)c; int checkSum = (Ascii + so_far) % 64; return checkSum; } char get_string_and_checksum() { while (1) { return getchar(); } } int main() { char c; int so_far; printf("Enter a string: "); c = get_string_and_checksum(); if (c == '.') { return 0; } else { so_far = generate_checksum(c, 0); while (1) { c = get_string_and_checksum(); if (c == '.') { int checkSum = so_far; if (checkSum == 0) { return 0; } so_far = -10; printf("checkSum = %d\n", checkSum); printf("Enter next string: "); } else { so_far = generate_checksum(c, so_far); } } } return 0; }