210701118

Ex-01/recognizetokens.c

@@ -0,0 +1,159 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+// Returns 'true' if the character is a DELIMITER.
+bool isDelimiter(char ch)
+{
+	if (ch == ' ' || ch == '+' || ch == '-' || ch == '*' || 
+		ch == '/' || ch == ',' || ch == ';' || ch == '>' || 
+		ch == '<' || ch == '=' || ch == '(' || ch == ')' || 
+		ch == '[' || ch == ']' || ch == '{' || ch == '}')
+		return (true);
+	return (false);
+}
+
+// Returns 'true' if the character is an OPERATOR.
+bool isOperator(char ch)
+{
+	if (ch == '+' || ch == '-' || ch == '*' || 
+		ch == '/' || ch == '>' || ch == '<' || 
+		ch == '=')
+		return (true);
+	return (false);
+}
+
+// Returns 'true' if the string is a VALID IDENTIFIER.
+bool validIdentifier(char* str)
+{
+	if (str[0] == '0' || str[0] == '1' || str[0] == '2' ||
+		str[0] == '3' || str[0] == '4' || str[0] == '5' || 
+		str[0] == '6' || str[0] == '7' || str[0] == '8' || 
+		str[0] == '9' || isDelimiter(str[0]) == true)
+		return (false);
+	return (true);
+}
+
+// Returns 'true' if the string is a KEYWORD.
+bool isKeyword(char* str)
+{
+	if (!strcmp(str, "if") || !strcmp(str, "else") ||
+		!strcmp(str, "while") || !strcmp(str, "do") || 
+		!strcmp(str, "break") || 
+		!strcmp(str, "continue") || !strcmp(str, "int")
+		|| !strcmp(str, "double") || !strcmp(str, "float")
+		|| !strcmp(str, "return") || !strcmp(str, "char")
+		|| !strcmp(str, "case") || !strcmp(str, "char")
+		|| !strcmp(str, "sizeof") || !strcmp(str, "long")
+		|| !strcmp(str, "short") || !strcmp(str, "typedef")
+		|| !strcmp(str, "switch") || !strcmp(str, "unsigned")
+		|| !strcmp(str, "void") || !strcmp(str, "static")
+		|| !strcmp(str, "struct") || !strcmp(str, "goto"))
+		return (true);
+	return (false);
+}
+
+// Returns 'true' if the string is an INTEGER.
+bool isInteger(char* str)
+{
+	int i, len = strlen(str);
+
+	if (len == 0)
+		return (false);
+	for (i = 0; i < len; i++) {
+		if (str[i] != '0' && str[i] != '1' && str[i] != '2'
+			&& str[i] != '3' && str[i] != '4' && str[i] != '5'
+			&& str[i] != '6' && str[i] != '7' && str[i] != '8'
+			&& str[i] != '9' || (str[i] == '-' && i > 0))
+			return (false);
+	}
+	return (true);
+}
+
+// Returns 'true' if the string is a REAL NUMBER.
+bool isRealNumber(char* str)
+{
+	int i, len = strlen(str);
+	bool hasDecimal = false;
+
+	if (len == 0)
+		return (false);
+	for (i = 0; i < len; i++) {
+		if (str[i] != '0' && str[i] != '1' && str[i] != '2'
+			&& str[i] != '3' && str[i] != '4' && str[i] != '5'
+			&& str[i] != '6' && str[i] != '7' && str[i] != '8'
+			&& str[i] != '9' && str[i] != '.' || 
+			(str[i] == '-' && i > 0))
+			return (false);
+		if (str[i] == '.')
+			hasDecimal = true;
+	}
+	return (hasDecimal);
+}
+
+// Extracts the SUBSTRING.
+char* subString(char* str, int left, int right)
+{
+	int i;
+	char* subStr = (char*)malloc(
+				sizeof(char) * (right - left + 2));
+
+	for (i = left; i <= right; i++)
+		subStr[i - left] = str[i];
+	subStr[right - left + 1] = '\0';
+	return (subStr);
+}
+
+// Parsing the input STRING.
+void parse(char* str)
+{
+	int left = 0, right = 0;
+	int len = strlen(str);
+
+	while (right <= len && left <= right) {
+		if (isDelimiter(str[right]) == false)
+			right++;
+
+		if (isDelimiter(str[right]) == true && left == right) {
+			if (isOperator(str[right]) == true)
+				printf("'%c' IS AN OPERATOR\n", str[right]);
+
+			right++;
+			left = right;
+		} else if (isDelimiter(str[right]) == true && left != right
+				|| (right == len && left != right)) {
+			char* subStr = subString(str, left, right - 1);
+
+			if (isKeyword(subStr) == true)
+				printf("'%s' IS A KEYWORD\n", subStr);
+
+			else if (isInteger(subStr) == true)
+				printf("'%s' IS AN INTEGER\n", subStr);
+
+			else if (isRealNumber(subStr) == true)
+				printf("'%s' IS A REAL NUMBER\n", subStr);
+
+			else if (validIdentifier(subStr) == true
+					&& isDelimiter(str[right - 1]) == false)
+				printf("'%s' IS A VALID IDENTIFIER\n", subStr);
+
+			else if (validIdentifier(subStr) == false
+					&& isDelimiter(str[right - 1]) == false)
+				printf("'%s' IS NOT A VALID IDENTIFIER\n", subStr);
+			left = right;
+		}
+	}
+	return;
+}
+
+// DRIVER FUNCTION
+int main()
+{
+	// maximum length of string is 100 here 
+	char str[100] = "int a = b + 1c; ";
+
+	parse(str); // calling the parse function
+
+	return (0);
+}