对C复杂声明的理解，到现在还是不行，这是从K&R 第二版中找到的一个程序， 可以加强理解：
dcl.h
View Code 1 #include < stdio.h > 2 #include < string .h > 3 #include < ctype.h > 4 5 #define MAXTOKEN 100 6 #define BUFSIZE 100 7 8 enum { NAME, PARENS, BRACKETS }; 9 10 char buf[BUFSIZE]; 11 int bufp = 0 ; 12 int getch( void ); 13 void ungetch( int c); 14 15 int tokentype; 16 char token[MAXTOKEN]; 17 char name[MAXTOKEN]; 18 char datatype[MAXTOKEN]; 19 char out [ 1000 ]; 20 21 void dcl( void ); 22 void dirdcl( void ); 23 int gettoken( void );
dcl.c
1 #include " dcl.h " 2 3 void dcl( void ) 4 { 5 int ns; 6 7 for (ns = 0 ; gettoken() == ' * ' ; ) 8 ns ++ ; 9 dirdcl(); 10 while (ns -- > 0 ) 11 strcat( out , " pointer to " ); 12 } 13 14 void dirdcl( void ) 15 { 16 int type; 17 18 if ( tokentype == ' ( ' ) { 19 dcl(); 20 if (tokentype != ' ) ' ) 21 printf( " error: missing )\n " ); 22 } else if (tokentype == NAME) { 23 strcpy(name, token); 24 } else { 25 printf( " error: expected name or (dcl)\n " ); 26 } 27 while ((type = gettoken()) == PARENS || type == BRACKETS) 28 if (type == PARENS) { 29 strcat( out , " function returning " ); 30 } else { 31 strcat( out , " array " ); 32 strcat( out , token); 33 strcat( out , " of " ); 34 } 35 } 36 37 int gettoken( void ) 38 { 39 int c; 40 char * p = token; 41 42 while ((c = getch()) == ' ' || c == ' \t ' ) 43 ; 44 if (c == ' ( ' ) { 45 if ((c = getch()) == ' ) ' ) { 46 strcpy(token, " () " ); 47 return tokentype = PARENS; 48 } else { 49 ungetch(c); 50 return tokentype = ' ( ' ; 51 } 52 } else if (c == ' [ ' ) { 53 for ( * p ++ = c; ( * p ++ = getch()) != ' ] ' ; ) 54 ; 55 * p = ' \0 ' ; 56 return tokentype = BRACKETS; 57 } else if (isalpha(c)) { 58 for ( * p ++ = c; isalpha(c = getch()); ) 59 * p ++ = c; 60 * p = ' \0 ' ; 61 ungetch(c); 62 return tokentype = NAME; 63 } else 64 return tokentype = c; 65 } 66 67 int getch( void ) 68 { 69 return (bufp > 0 ) ? buf[ -- bufp] : getchar(); 70 } 71 void ungetch( int c) 72 { 73 if (bufp >= BUFSIZE) 74 printf( " ungetch: too many characters\n " ); 75 else 76 buf[bufp ++ ] = c; 77 } 78 79 int main( void ) 80 { 81 while (gettoken() != EOF) { 82 strcpy(datatype, token); 83 out [ 0 ] = ' \0 ' ; 84 dcl(); 85 if (tokentype != ' \n ' ) 86 printf( " syntax error\n " ); 87 printf( " %s: %s %s\n " , name, out , datatype); 88 } 89 return 0 ; 90 }