Expression calculation (replace an infix expression with a suffix prefix expression)

An expression consisting of addition, subtraction, multiplication, division, and parentheses is provided to calculate the value of the expression and the prefix and suffix expression of the expression.

# Include
 
  
# Include
  
   
# Define Inf 1e9struct tree {double date; char ch; tree * l, * r; tree () {ch = '\ 0'; date = 0; l = r = NULL ;}}; double judge (char * s, int x, int y, double & n) {double num = 0; for (int I = x; I
   
    
= '0' & s [I] <= '9') {num = num * 10 + s [I]-'0';} else return 0; return n = num;} tree * build (char * s, int x, int y) {tree * now = new tree; double num = Inf; judge (s, x, y, num); // printf ("% c \ n", s [x]); if (num! = Inf) {now-> date = num; return now;} int p = 0, c1 =-1, c2 =-1; for (int I = x; I
    
     
L = build (s, x, c1); now-> r = build (s, c1 + 1, y); now-> ch = s [c1]; return now;} double dfs (tree * p) {if (! P) return 0; if (p-> l = p-> r & p-> l = NULL) return p-> date; switch (p-> ch) {case '+': return p-> date = dfs (p-> l) + dfs (p-> r); break; case '-': return p-> date = dfs (p-> l)-dfs (p-> r); break; case '*': return p-> date = dfs (p-> l) * dfs (p-> r); break; case '/': return p-> date = dfs (p-> l)/dfs (p-> r); break;} return 0;} void dfs (tree * p, int choose) {if (! P) return; if (p-> l = p-> r & p-> l = NULL) {printf ("% g ", p-> date);} if (! Choose) {printf ("% c", p-> ch); dfs (p-> l, choose); dfs (p-> r, choose );} else {dfs (p-> l, choose); dfs (p-> r, choose); printf ("% c", p-> ch );}} char s [1005]; int main () {tree * root = NULL; while (gets (s) = NULL) {root = NULL; int len = strlen (s ); root = build (s, 0, len); double ans = dfs (root); puts ("prefix expression:"); dfs (root, 0 ); puts (""); puts ("suffix expression:"); dfs (root, 1); puts (""); printf ("% s = % g \ n ", s, ans);} return 0 ;}
    
   
  
 

The above cannot be calculated as 5 *-6, and the following is corrected.

# Include
 
  
# Include
  
   
# Define Inf 1e9struct tree {double date; char ch; tree * l, * r; tree () {ch = '\ 0'; date = 0; l = r = NULL ;}}; char st [1005]; double judge (char * s, int x, int y, double & n) {double num = 0; for (int I = x; I
   
    
= '0' & s [I] <= '9') {num = num * 10 + s [I]-'0';} else return 0; return n = num;} int is_operator (char c) {if (c = '+' | c = '-' | c = '*' | c = '/') return 1; return 0;} tree * build (char * s, int x, int y) {tree * now = new tree; double num = Inf; judge (s, x, y, num); // printf ("% c \ n", s [x]); if (num! = Inf) {now-> date = num; return now;} int p = 0, c1 =-1, c2 =-1; for (int I = x; I
    
     
L = build (s, x, c1); now-> r = build (s, c1 + 1, y); now-> ch = s [c1]; return now;} double dfs (tree * p) {if (! P) return 0; if (p-> l = p-> r & p-> l = NULL) return p-> date; switch (p-> ch) {case '+': return p-> date = dfs (p-> l) + dfs (p-> r); break; case '-': return p-> date = dfs (p-> l)-dfs (p-> r); break; case '*': return p-> date = dfs (p-> l) * dfs (p-> r); break; case '/': return p-> date = dfs (p-> l)/dfs (p-> r); break;} return 0;} void dfs (tree * p, int choose) {if (! P) return; if (p-> l = p-> r & p-> l = NULL) {printf ("% g ", p-> date);} if (! Choose) {printf ("% c", p-> ch); dfs (p-> l, choose); dfs (p-> r, choose );} else {dfs (p-> l, choose); dfs (p-> r, choose); printf ("% c", p-> ch );}} char s [1005]; int main () {tree * root = NULL; while (gets (s )! = NULL) {root = NULL; int len = strlen (s); root = build (s, 0, len); double ans = dfs (root ); puts ("prefix expression:"); dfs (root, 0); puts (""); puts ("suffix expression:"); dfs (root, 1 ); puts (""); printf ("% s = % g \ n", s, ans);} return 0 ;}