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pratical1.c
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pratical1.c
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#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_LENGTH 100
bool isDelimiter(char chr) {
return (chr == ' ' || chr == '+' || chr == '-' ||
chr == '*' || chr == '/' || chr == ',' ||
chr == ';' || chr == '%' || chr == '>' ||
chr == '<' || chr == '=' || chr == '(' ||
chr == ')' || chr == '[' || chr == ']' ||
chr == '{' || chr == '}');
}
bool isOperator(char chr) {
return (chr == '+' || chr == '-' || chr == '*' ||
chr == '/' || chr == '>' || chr == '<' ||
chr == '=');
}
bool isValidIdentifier(char* str) {
return (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]));
}
bool isKeyword(char* str) {
const char* keywords[] = { "auto", "break", "case", "char",
"const", "continue", "default", "do",
"double", "else", "enum", "extern",
"float", "for", "goto", "if",
"int", "long", "register", "return",
"short", "signed", "sizeof", "static",
"struct", "switch", "typedef", "union",
"unsigned", "void", "volatile", "while" };
for (int i = 0; i < sizeof(keywords) / sizeof(keywords[0]); i++) {
if (strcmp(str, keywords[i]) == 0) {
return true;
}
}
return false;
}
bool isInteger(char* str) {
int i = 0;
if (str == NULL || *str == '\0') {
return false;
}
while (isdigit(str[i])) {
i++;
}
return str[i] == '\0';
}
char* getSubstring(char* str, int start, int end) {
int length = strlen(str);
int subLength = end - start + 1;
char* subStr = (char*)malloc((subLength + 1) * sizeof(char));
strncpy(subStr, str + start, subLength);
subStr[subLength] = '\0';
return subStr;
}
int lexicalAnalyzer(char* input) {
int left = 0, right = 0;
int len = strlen(input);
while (right <= len && left <= right) {
if (!isDelimiter(input[right]))
right++;
if (isDelimiter(input[right]) && left == right) {
if (isOperator(input[right]))
printf("Token: Operator, Value: %c\n", input[right]);
right++;
left = right;
}
else if (isDelimiter(input[right]) && left != right ||
(right == len && left != right)) {
char* subStr = getSubstring(input, left, right - 1);
if (isKeyword(subStr))
printf("Token: Keyword, Value: %s\n", subStr);
else if (isInteger(subStr))
printf("Token: Integer, Value: %s\n", subStr);
else if (isValidIdentifier(subStr) && !isDelimiter(input[right - 1]))
printf("Token: Identifier, Value: %s\n", subStr);
else if (!isValidIdentifier(subStr) && !isDelimiter(input[right - 1]))
printf("Token: Unidentified, Value: %s\n", subStr);
left = right;
}
}
return 0;
}
int main() {
char lex_input[MAX_LENGTH] = "int a = b + c";
printf("For Expression \"%s\":\n", lex_input);
lexicalAnalyzer(lex_input);
printf(" \n");
char lex_input01[MAX_LENGTH] = "int x=ab+bc+30+switch+ 0y ";
printf("For Expression \"%s\":\n", lex_input01);
lexicalAnalyzer(lex_input01);
return (0);
}