C language - simple lexical analyzer

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int P, m, SYN, n-, SUM; // P and m, acts as a pointer, used to point to the next character or back one character, syn used to determine the type of character.
                          // n is the loop control variable, sum for discriminating whether or integer overflow.
char token [10], prog [ 80]; // global variables, arrays for receiving a keyboard input, another for lexical analysis.
char ch; // array of characters one by one removed from the keyboard input, the determination to do.
char * keywords [7] = { "begin", "else", "if", "while", "do", "end", "then"}; // key character array. To compare strings and keyboard input

void Scaner () // lexical analyzer
{P = 0;
     n-= 0;
    CH PROG = [P ++]; // array of characters from the keyboard, and reading a character used to make discrimination. p points to the next character.
    for (n = 0; n ++ ; n <10) // initialize after storing for discriminating a character array of characters
        token = '[n];'
   when while (ch == '') // read character is not empty , it is judged if
    {
        CH = PROG [the p-++]; // empty, p has been going down.
        ++ P;
    }
    IF ((CH> = 'A' && CH <= 'Z') || (CH <= 'the Z' && CH> = 'A')) // if the letter.
    {
        M = 0;
        the while ((CH> = 'A' && CH <= 'Z') || (CH <= 'the Z' && CH> = 'A')) // cycle, reads a next character for the letter .
        {
            Token [++ m] = CH;



        p--; // p rollback one, because at this time if the conditions are not satisfied.
        syn = 10; // letter kind as code, is 10. The
        (n-= 0; n-<. 7; n-++) for
        IF (strcmp (token, Keywords [n-]) == 0) // read into the array of characters and comparing keyword string array
        {
            SYN = n-+. 1; // if the same kind of key codes do not return 1-6
            BREAK;
        }
            }
    the else IF (CH> = '0' && CH <= '. 9') // If the character is read into the figures.
    {
        SUM = 0;
        the while (CH <= '. 9' && CH> = '0') // accumulated.
        {
            SUM = SUM + 10 * CH-'0 '; // Since character, so to carry manually. sum multiplied by 10,
            CH = PROG [P ++];
        }
        the P--;
        SYN =. 11;
        IF (sum> 32767) // determine whether the overflow. int type (C language) up to 32767, the minimum is -32 766
            syn = -1; // do not code seed -1, indicating overflow.
    }
    The else Switch (CH) // if the operator is
    {
        Case '<':
          m = 0;
          token [++ m] = CH;
          CH PROG = [P ++];
          IF (CH == '>') // formed angle brackets <>
          {
              token [++ m] = CH;
              SYN = 21 is; // angle brackets kind as code
          }
          the else IF (CH == '=') is formed // <=
          {
              token [++ m] = CH;
              SYN = 22 is;
          }
          the else
          {
              SYN = 20 is;
              the P--;
          }
          BREAK;
        case '>': // and <Similarly
            m = 0;
            token [m ++] = CH;
            CH = PROG [P ++];
            IF (CH == '<')
            {
                token [m ++] = CH;
                SYN = 21 is;
            }
            the else IF (CH == '=')
            {
                token [++ m] = CH;
                 SYN = 24;
            }
            the else
            {
                SYN = 25;
                the P--;
            }
            BREAK;
        Case '(': // angle brackets Similarly
            m 0 =;
            token [++ m] = CH;
            ch=prog[p++];
            if(ch==')')
            {
                token[m++]=ch;
                syn = 26;
            }
            else
            {
                syn = 27;
                p--;
            }
            break;
        case ')':
            m=0;
            token[m++]=ch;
            ch=prog[p++];
            if(ch=='(')
            {
                token[m++]=ch;
                syn=26;
            }
            else
            {
                syn=27;
                the P--;
            }
            BREAK;
        Case '+': token [0] = CH; = 12 is SYN; BREAK; // some other process operators
        case '-': token [0 ] = ch; syn = 13; break ;
        Case '*': token [0] = CH; SYN = 14; BREAK;
        Case '/': token [0] = CH; SYN = 15; BREAK;
        Case '!': token [0] = CH; SYN = 16; BREAK;
        Case ':': token [0] = CH; SYN =. 17; BREAK;
        Case ';': token [0] = CH; SYN = 18 is; BREAK;
        Case '#': token [0] CH =; SYN = 0; BREAK;
        default: SYN = -1; BREAK;
    }
}

main int ()
{P = 0;
    the printf ( "Please Enter A String: \ n-");
    the gets (PROG); // set the keyboard input of characters.
    do
    {
        Scaner (); // do lexical analysis
       IF (SYN <10 && SYN> 0)
        {the printf ( "This IS Keywords \ n-!"); BREAK;} // keyword
       the else IF (SYN == 10)
       {the printf ( "This is a words \ n! "); break;} // identifier
       the else IF (SYN ==. 11)
        {the printf () "This IS A number \ n-!"; BREAK;} // digital
       the else
        {the printf ( "Other words \ n!") ; break;} // operator or terminator #
    }
    ! the while (SYN = 0);
    return 0;
}