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  1. #include <stdio.h>
  2. #include <ctype.h>
  3. #include <string.h>
  4.  
  5. typedef struct
  6. {
  7.     char lexeme[100];
  8.     char type[20];
  9. } Token;
  10.  
  11. const char* keywords[] = {"int", "float", "if", "else", "while", "return", "void", "char", "for", "double"};
  12. const int num_keywords = sizeof(keywords) / sizeof(keywords[0]);
  13.  
  14. int isKeyword(const char* token)
  15. {
  16.     for (int i = 0; i < num_keywords; i++)
  17.     {
  18.         if (strcmp(token, keywords[i]) == 0)
  19.         {
  20.             return 1;
  21.         }
  22.     }
  23.     return 0;
  24. }
  25.  
  26. Token classifyToken(const char *token)
  27. {
  28.     Token t;
  29.     strcpy(t.lexeme, token);
  30.  
  31.     if (isKeyword(token))
  32.         strcpy(t.type, "KEYWORD");
  33.     else if (isdigit(token[0]))
  34.         strcpy(t.type, "NUMBER");
  35.     else if (isalpha(token[0]) || token[0] == '_')
  36.         strcpy(t.type, "IDENTIFIER");
  37.     else if (strchr("+-*/=<>!", token[0]))
  38.         strcpy(t.type, "OPERATOR");
  39.     else if (strchr(";(),{}", token[0]))
  40.         strcpy(t.type, "DELIMITER");
  41.     else
  42.         strcpy(t.type, "UNKNOWN");
  43.  
  44.     return t;
  45. }
  46.  
  47. void lexicalAnalyzer(const char *input)
  48. {
  49.     char token[100];
  50.     int index = 0;
  51.  
  52.     for (int i = 0; i < strlen(input); i++)
  53.     {
  54.         char ch = input[i];
  55.  
  56.         if (isspace(ch))
  57.         {
  58.             if (index > 0)
  59.             {
  60.                 token[index] = '\0';
  61.                 Token t = classifyToken(token);
  62.                 printf("%s: %s\n", t.type, t.lexeme);
  63.                 index = 0;
  64.             }
  65.         }
  66.         else if (strchr("+-*/=<>!", ch) || strchr(";(),{}", ch))
  67.         {
  68.             if (index > 0)
  69.             {
  70.                 token[index] = '\0';
  71.                 Token t = classifyToken(token);
  72.                 printf("%s: %s\n", t.type, t.lexeme);
  73.                 index = 0;
  74.             }
  75.  
  76.             char next = input[i + 1];
  77.  
  78.             if (strchr("+-*/=<>!", ch) && next == '=')
  79.             {
  80.                 token[0] = ch;
  81.                 token[1] = '=';
  82.                 token[2] = '\0';
  83.                 Token t = classifyToken(token);
  84.                 printf("%s: %s\n", t.type, t.lexeme);
  85.                 i++;
  86.             }
  87.             else
  88.             {
  89.                 token[0] = ch;
  90.                 token[1] = '\0';
  91.                 Token t = classifyToken(token);
  92.                 printf("%s: %s\n", t.type, t.lexeme);
  93.             }
  94.         }
  95.         else
  96.         {
  97.             token[index++] = ch;
  98.         }
  99.     }
  100.  
  101.     if (index > 0)
  102.     {
  103.         token[index] = '\0';
  104.         Token t = classifyToken(token);
  105.         printf("%s: %s\n", t.type, t.lexeme);
  106.     }
  107. }
  108.  
  109. int main()
  110. {
  111.    printf("Enter a simple C code snippet: ");
  112.     char input[100] = "+= -= *= /= <= >= != ==";
  113.  
  114.  
  115.     printf("\nTokens Found:\n");
  116.     lexicalAnalyzer(input);
  117.  
  118.     return 0;
  119. }
  120.  
Success #stdin #stdout 0s 5328KB
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stdin
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Standard input is empty
stdout
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Enter a simple C code snippet: 
Tokens Found:
OPERATOR: +=
OPERATOR: -=
OPERATOR: *=
OPERATOR: /=
OPERATOR: <=
OPERATOR: >=
OPERATOR: !=
OPERATOR: ==
https://ideone.com/PoAVjd
First Task
language:
C (gcc 8.3)
created:
22 hours ago
visibility:
public

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