c 언어를 c++로 변환을 해야 하는데 아래 코드를 어떻게 바꺼야

아래 씨언어를 C++로 바꺼야 하는데 제가 씨를 잘몰라서요

어디를 어떻게 바꺼야 하는지 가르쳐 주세요 ..

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

struct tokentype scanner()
{
struct tokentype scanner()
{
struct tokentype token;
int i, j, k, num;
char ch, id[ID_LENGTH];

token.number = tnull;
do {
while (isspace(ch = getchar())); /* state 1: skip blanks */
if (isalpha(ch)) { /* state 2: identifier or keyword */
i = 0;
do {
if (i<ID_LENGTH) id[i++] = ch;
ch = getchar();
} while (isalnum(ch));
id[i] = '\0';
ungetc(ch, stdin); /* retract */
/* find the idenfier in the keyword table*/
i = 0; j = NUMKEYWORD-1;
do { /* binary search */
k = (i+j) / 2;
if (stcmp(id, keyword[k]) >= 0) i= k + 1;
if (stcmp(id, keyword[k]) <= 0) i= k - 1;
} while ( i<= j);
if ((i-1)>j) /* found, keyword exit */
token.number = tnum[k];
else { /* not found, idenfier exit */
token.number = tident;
stcpy(token.value.id, id);
}
} /* end of idenfier or keyword */
else if (isdiget(ch)) { /* state 5: number */
num = 0;
do {
num = 10*num + (int)(ch - '0');
ch = getchar();
} while (isdigit(ch));
nugetc(ch, stdin); /* retract */
token.nimber = tnumber;
token.value.num = num;
} /* number */
else swich (ch) { /* spcial characters */
case '(': /* state 7 */
ch = getchar();
if (ch=='*') /* comment */
do { while (ch != '*') ch = getchar;
ch = getchar();
} while (ch != ')');
else { token.number = tlparen;
ungetc(ch, stdin); /* retract */
}
break;
case '<': /* state 11 */
ch = getchar();
if (ch == '>') token.number = tnequal;
else if (ch == '=') token.number = tlesse;
else { token.number = tless;
ungetc(ch.stdin); /* retract */
}
break;
case '>': /* state 15 */
ch = getchar();
if (ch == '=') token.number = tgreate;
else { token.number = tgreate;
ungetc(ch.stdin); /* retract */
}
break;
case ':': /* state 18 */
ch = getchar();
if (ch == '=') token.number = tassign;
else { token.number = tcolon;
ungetc(ch.stdin); /* retract */
}
break;
case '.': /* state 21 */
ch = getchar();
if (ch == '.') token.number = tddot;
else { token.number = tdot;
ungetc(ch.stdin); /* retract */
}
break;
case '=': token.number = tequal; break;
case ')': token.number = trparen; break;
case '+': token.number = tplus; break;
case '-': token.number = tminus; break;
case '*': token.number = ttimes; break;
case ';': token.number = tsemicolon; break;
case ',': token.number = tcomma; break;
case '[': token.number = tlbracket; break;
case ']': token.number = trbracket; break;
case EOF: token.number = teof; break;
} /* switch end */
} while (token.number == tnull);
return token;
} /* end of scanner */