• 2 Posts
  • 87 Comments
Joined 3 years ago
Cake day: July 22nd, 2023
  • mcmodknower@programming.devtoC Programming Language@programming.dev•[Beginner] How do I save previous input in variables/arrays?English
    4·
    4 months ago

    For saving the history inside of one program run, an array is enough. For saving the history over multiple program runs (over closing by typing and invalid character or ctrl+c and restarting it), you would need to store it in a file.

    You can already print the last conversion by reading the value of f_value/c_value without writing to it (note that if no conversion of that type has happened before, you will get garbage, and that you will have to modify the if at the start of the loop to check for ‘x’ too):

    		if (choice == 'x') {  // x is the letter left of c, so i chose it as an easy example
			// we want to print the previous conversion, so we don't want to read in a new value.
			// printf("\nEnter the temperature in Celcius: ");  
			// scanf("%d", &c_value);  
			// you might need to comment this getchar() back in so your program skips over the enter after the x, but i am not sure.
			// getchar();  
			// no modification of the following line is needed, as the c_value of the last celcius conversion was never written too and as such still exists.
			printf("\n%d degrees Celcius is %.1f degrees Fahrenheit.\n", c_value, toFahrenheit(c_value));  
		}

    For a longer history you need some extra places to store the numbers. if you use an array, you need to store the length of the history too, since c does not store how far into the array you have written.

    // at the start of your main function, where you also declare the other variables
	// allocate the array with fixed length
	int last_c_values[16];
	// and store how many values you've written to it. Initialize it to zero so you don't do garbage with it later on.
	int last_c_values_count = 0;

// after printing the conversion from celsius to farenheit
			if (last_c_values_count < 16) // we can't handle a history longer than that yet
				// copy over the current value into the array, the first one will be at index 0
				last_c_values[last_c_values_count] = c_value;
				// increase the counter so the next value will be at the next place
				last_c_values_count = last_c_values_count + 1;
				// or shorter: last_c_values_count++;
			}

//and the new choice for printing the stuff
		if (choice == 'x') {  // x is the letter left of c, so i chose it as an easy example
			// start at 0, as long as i is below last_c_values_count, increment i by one at the end of each loop run
			for (int i = 0; i < last_c_values_count; i++) {
				// copy the value from last_c_values at index i into c_value
				c_value = last_c_values[i]; 
				// and do the same calculation as before again.
				printf("\n%d degrees Celcius is %.1f degrees Fahrenheit.\n", c_value, toFahrenheit(c_value));  
			}
		}

    PS: the for loop in here is equivalent to the following while loop:

    			int i = 0;
			while (i < last_c_values_count) {
				// copy the value from last_c_values at index i into c_value
				c_value = last_c_values[i]; 
				// and do the same calculation as before again.
				printf("\n%d degrees Celcius is %.1f degrees Fahrenheit.\n", c_value, toFahrenheit(c_value));  
				i++;
			}
  • mcmodknower@programming.devtoProgramming@programming.dev•What was the smallest python hobby project you worked on?English
    2·
    5 months ago

    My smallest python program was for filtering wifi names according to patterns. I hab collected some wifi names atomatically via sone other programs, and had them sitting in a text file with one name per line (a very simple data format). I wanted to find interesting names out of it, but didn’t want to spend much time scrolling through hundreds of names following the same pattern, like ISP-12C5, ISP-3F4B, … So i invented my own pattern syntax for very simple patterns, (ISP-%4Ax for ISP- followed by 4 hexadecimal digits with only capital letters), and wrote up a python script that read patterns from a file, and then filtered the standard input against those patters. any line not matching any pattern was then printed.

    In short it was a small project that i wanted to do, with simple data formats that i could easily parse and relatively simpel logic that i had ideas how to implement while designing the patterns. And i had some data to test it on.

    So my advice is similar to the other people here: look for things you are interested in or you need that sound simple to program, and then go on and program one of them. No problem is too small to make a program for.