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Lex Program to print the total characters, white spaces, tabs in the given input file

  • Difficulty Level : Hard
  • Last Updated : 30 Apr, 2019
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Lex is a computer program that generates lexical analyzers. Lex reads an input stream specifying the lexical analyzer and outputs source code implementing the lexer in the C programming language.

The commands for executing the lex program are:

lex abc.l (abc is the file name)
cc lex.yy.c -lfl
./a.out

Let’s see Lex program to print the total characters, white spaces, tabs in the given input file.

Below is the implementation:




/* Lex program to print the total characters, 
white spaces, tabs in the given input file.
*/
  
%
{
    int n, w, c;
    %
}
% %
\n { n++; }
[^ \n\t] +
{
    w++;
    c = c + yyleng;
}
.c++;
% % int yywrap(void)
{
    return 1;
}
  
  
main()
{
    extern FILE* yyin;
    yyin = fopen("input.txt", "r");
    yylex();
    printf("Line= %d word=%d total char=%d \n", n, w, c);
}

Input:



Output:

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