#include  #include  #include  #include  // 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] = '';  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 OPERATORn' 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 KEYWORDn' subStr);  else if (isInteger(subStr) == true)  printf(''%s' IS AN INTEGERn' subStr);  else if (isRealNumber(subStr) == true)  printf(''%s' IS A REAL NUMBERn' subStr);  else if (validIdentifier(subStr) == true  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS A VALID IDENTIFIERn' subStr);  else if (validIdentifier(subStr) == false  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS NOT A VALID IDENTIFIERn' 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); } 

#include  #include  #include  #include  // 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] = '';  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 OPERATORn' 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 KEYWORDn' subStr);  else if (isInteger(subStr) == true)  printf(''%s' IS AN INTEGERn' subStr);  else if (isRealNumber(subStr) == true)  printf(''%s' IS A REAL NUMBERn' subStr);  else if (validIdentifier(subStr) == true  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS A VALID IDENTIFIERn' subStr);  else if (validIdentifier(subStr) == false  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS NOT A VALID IDENTIFIERn' 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); } 

import java.util.Arrays; public class Parser {  public static boolean isDelimiter(char ch) {  return ' +-*/ ;><=()[]{}'.indexOf(ch) != -1;  }  public static boolean isOperator(char ch) {  return '+-*/><='.indexOf(ch) != -1;  }  public static boolean validIdentifier(String str) {  if (str.isEmpty() || Character.isDigit(str.charAt(0)) || isDelimiter(str.charAt(0)))  return false;  return true;  }  public static boolean isKeyword(String str) {  String[] keywords = { 'if' 'else' 'while' 'do' 'break' 'continue' 'int' 'double' 'float' 'return' 'char' 'case' 'sizeof' 'long' 'short' 'typedef' 'switch' 'unsigned' 'void' 'static' 'struct' 'goto' };  return Arrays.asList(keywords).contains(str);  }  public static boolean isInteger(String str) {  if (str.isEmpty())  return false;  for (int i = 0; i < str.length(); i++) {  if (!Character.isDigit(str.charAt(i)) && !(str.charAt(i) == '-' && i == 0))  return false;  }  return true;  }  public static boolean isRealNumber(String str) {  if (str.isEmpty())  return false;  boolean hasDecimal = false;  for (int i = 0; i < str.length(); i++) {  if (!Character.isDigit(str.charAt(i)) && str.charAt(i) != '.' && !(str.charAt(i) == '-' && i == 0))  return false;  if (str.charAt(i) == '.')  hasDecimal = true;  }  return hasDecimal;  }  public static String subString(String str int left int right) {  return str.substring(left right + 1);  }  public static void parse(String str) {  int left = 0 right = 0;  int len = str.length();  while (right <= len && left <= right) {  if (!isDelimiter(str.charAt(right)))  right++;  if (isDelimiter(str.charAt(right)) && left == right) {  if (isOperator(str.charAt(right)))  System.out.println(''' + str.charAt(right) + '' IS AN OPERATOR');  right++;  left = right;  } else if (isDelimiter(str.charAt(right)) && left != right || (right == len && left != right)) {  String subStr = subString(str left right - 1);  if (isKeyword(subStr))  System.out.println(''' + subStr + '' IS A KEYWORD');  else if (isInteger(subStr))  System.out.println(''' + subStr + '' IS AN INTEGER');  else if (isRealNumber(subStr))  System.out.println(''' + subStr + '' IS A REAL NUMBER');  else if (validIdentifier(subStr) && !isDelimiter(str.charAt(right - 1)))  System.out.println(''' + subStr + '' IS A VALID IDENTIFIER');  else if (!validIdentifier(subStr) && !isDelimiter(str.charAt(right - 1)))  System.out.println(''' + subStr + '' IS NOT A VALID IDENTIFIER');  left = right;  }  }  }  public static void main(String[] args) {  String str = 'int a = b + 1c; ';  parse(str);  } } 

def is_delimiter(ch): return ch in ' +-*/ ;><=()[]{}' def is_operator(ch): return ch in '+-*/><=' def valid_identifier(str): if not str or str[0].isdigit() or is_delimiter(str[0]): return False return True def is_keyword(str): keywords = ['if' 'else' 'while' 'do' 'break' 'continue' 'int' 'double' 'float' 'return' 'char' 'case' 'sizeof' 'long' 'short' 'typedef' 'switch' 'unsigned' 'void' 'static' 'struct' 'goto'] return str in keywords def is_integer(str): if not str: return False for i in range(len(str)): if not str[i].isdigit() and not (str[i] == '-' and i == 0): return False return True def is_real_number(str): if not str: return False has_decimal = False for i in range(len(str)): if not str[i].isdigit() and str[i] != '.' and not (str[i] == '-' and i == 0): return False if str[i] == '.': has_decimal = True return has_decimal def sub_string(str left right): return str[left:right + 1] def parse(str): left = 0 right = 0 len_str = len(str) while right <= len_str and left <= right: if not is_delimiter(str[right]): right += 1 if is_delimiter(str[right]) and left == right: if is_operator(str[right]): print(f''{str[right]}' IS AN OPERATOR') right += 1 left = right elif is_delimiter(str[right]) and left != right or (right == len_str and left != right): sub_str = sub_string(str left right - 1) if is_keyword(sub_str): print(f''{sub_str}' IS A KEYWORD') elif is_integer(sub_str): print(f''{sub_str}' IS AN INTEGER') elif is_real_number(sub_str): print(f''{sub_str}' IS A REAL NUMBER') elif valid_identifier(sub_str) and not is_delimiter(str[right - 1]): print(f''{sub_str}' IS A VALID IDENTIFIER') elif not valid_identifier(sub_str) and not is_delimiter(str[right - 1]): print(f''{sub_str}' IS NOT A VALID IDENTIFIER') left = right if __name__ == '__main__': str = 'int a = b + 1c; ' parse(str)