add lab04 solution

lab04/Makefile

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+# Compiler and flags
+CC = gcc
+CFLAGS = -Wall -std=c11
+
+#Input file
+INPUT = input2.txt
+OUTPUT = output.txt
+REF = ref2.txt
+# Source file
+SRCS = lab4.c
+# Output
+TARGET = lab4.out
+
+# Default target
+all: $(TARGET)
+
+# Rule to build the executable
+$(TARGET): $(SRCS)
+	$(CC) $(CFLAGS) $(SRCS) -o $(TARGET)
+
+
+convert_input: $(INPUT)
+	dos2unix $(INPUT)
+
+convert_output: $(OUTPUT)
+	dos2unix $(OUTPUT)
+
+check: $(OUTPUT) $(REF)
+	@diff -q $(OUTPUT) $(REF) > /dev/null; \
+	if [ $$? -eq 0 ]; then \
+		echo "Pass"; \
+	else \
+		echo "Fail"; \
+	fi
+
+# Rule to run the program
+run: $(TARGET)
+	./$(TARGET) $(INPUT) $(OUTPUT) 3
+
+# Rule to clean generated files
+clean:
+	rm -f $(TARGET)

lab04/input.txt

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+Science and technology are driving forces for innovation.

lab04/input2.txt

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+Elephants are the largest land animals on Earth.

lab04/lab4.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+// A01385066
+
+/**
+ * encrypt_text takes in an input path, encrypts the contents of
+ * the file from input path by a given shift amount. Then writes 
+ * the encrypted content to the specified output path.
+ * 
+ * @param inputPath  char[] - input path of file to encrypt
+ * @param outputPath char[] - output path of encrypted file
+ * @param shift      int    - number to shift characters by
+ * @author Braeden Sowinski
+ */
+void encrypt_text(char inputPath[], char outputPath[], int shift) 
+{
+
+	FILE *readFile;
+	FILE *writeFile;
+	char character;
+
+	readFile  = fopen(inputPath, "r");
+	writeFile = fopen(outputPath, "w");
+
+	if (readFile == NULL)
+	{
+		printf("Error opening file: \"%s\"\n", inputPath);
+		return;
+	}
+
+	if (writeFile == NULL)
+	{
+		printf("Error opening file: \"%s\"\n", outputPath);
+		return;
+	}
+
+	// Iterate over characters till end of file
+	while((character = fgetc(readFile)) != EOF)
+	{
+
+		if ((character >= 'A' && character <= 'Z') || 
+			(character >= 'a' && character <= 'z')) 
+		{
+
+			/*
+			* if capital letter and adding shift to character goes beyond 'Z'
+			* then shift character to 'A' - 1 before adding shift.
+			*/
+			if (character <= 'Z' && character >= 'A' && (character + shift) > 'Z')
+			{
+				character -= ('Z' + 1) - 'A';
+			}
+
+			character += shift;
+
+			/*
+			* if character goes beyond alphabet (> 'z') then
+			* shift character back by the number of lower case
+			* letters.
+		 	*/
+			if (character > 'z')
+			{
+				character -= ('z' + 1) - 'a';
+			}
+		}
+
+		fputc(character, writeFile);
+	}
+
+	fclose(readFile);
+	fclose(writeFile);
+
+	return;
+}
+
+int main(int argc, char *argv[])
+{
+
+	if (argc != 4)
+	{
+		printf("Usage: %s <input_file> <output_file> <shift>\n", argv[0]);
+		return 1;
+	}
+
+	char *inputPath;
+	char *outputPath;
+	int  shift;
+
+	inputPath  = argv[1];
+	outputPath = argv[2];
+	shift      = atoi(argv[3]);
+
+	encrypt_text(inputPath, outputPath, shift);
+
+	return 0;
+}

lab04/output.txt

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+Hohskdqwv duh wkh odujhvw odqg dqlpdov rq Hduwk.

lab04/ref.txt

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+Vflhqfh dqg whfkqrorjb duh gulylqj irufhv iru lqqrydwlrq.

lab04/ref2.txt

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+Hohskdqwv duh wkh odujhvw odqg dqlpdov rq Hduwk.