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#include <stdio.h>
#include <string.h>
#include <ctype.h>
/* The C Programming Language: 2nd Edition
*
* Exercise 5-19: Modify `undcl` so that it does not add redundant parentheses
* to declarations.
*
* Notes: The only circumstance that `undcl` will add extra parens is when it
* comes across a pointer. So we look ahead and count pointers, then add them
* all at once before output. It's a fairly simple fix.
*/
#define MAXTOKEN 100
#define BUFSIZE 100
#define MAXPTR 10
enum { NAME, PARENS, BRACKETS, TYPE };
int gettoken(void);
int getch(void);
void ungetch(int);
char buf[BUFSIZE];
int bufp = 0;
int tokentype;
char token[MAXTOKEN];
char name[MAXTOKEN];
char datatype[MAXTOKEN];
char out[1000];
int gettoken(void) {
int c;
char *p = token;
while ((c = getch()) == ' ' || c == '\t') {
}
if (c == '(') {
if ((c = getch()) == ')') {
strcpy(token, "()");
return tokentype = PARENS;
} else {
ungetch(c);
return tokentype = '(';
}
} else if (c == '[') {
for (*p++ = c; (*p++ = getch()) != ']';) {
}
*p = '\0';
return tokentype = BRACKETS;
} else if (isalpha(c)) {
for (*p++ = c; isalnum(c = getch());) {
*p++ = c;
}
*p = '\0';
ungetch(c);
return tokentype = NAME;
} else {
return tokentype = c;
}
}
int getch(void) {
return (bufp > 0) ? buf[--bufp] : getchar();
}
void ungetch(int c) {
if (bufp >= BUFSIZE) {
printf("ungetch: Too many characters.\n");
} else {
buf[bufp++] = c;
}
}
int main(void) {
int type, pcount, i, c;
char temp[MAXTOKEN];
char p[MAXPTR];
while (gettoken() != EOF) {
strcpy(out, token);
while ((type = gettoken()) != '\n') {
if (type == PARENS || type == BRACKETS) {
strcat(out, token);
} else if (type == '*') {
pcount++;
while ((c = getch()) == '*' || c == ' ') {
if (c == '*') {
if (pcount < (MAXPTR - 1)) {
pcount++;
} else {
break;
}
}
}
ungetch(c);
for (i = 0; i < pcount; i++) {
p[i] = '*';
}
pcount = 0;
p[i] = '\0';
sprintf(temp, "(%s%s)", p, out);
strcpy(out, temp);
} else if (type == NAME) {
sprintf(temp, "%s %s", token, out);
strcpy(out, temp);
} else {
printf("Invalid input at %s\n", token);
}
}
printf("%s\n", out);
}
return 0;
}
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