Program to parse a string using Operator Precedence parsing in C++.
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#include<conio.h> #include<stdio.h> #include<stdlib.h> int Operator_Position_Finder(char ); #define node struct Basic_tree int T4Tutorials[5][5]={ {1,0,0,1,1}, {1,1,0,1,1}, {0,0,0,2,3}, {1,1,3,1,1}, {0,0,0,3,2}}; int tos=-1; void T4Tutorials_value(void); //node create_node(char,*node);void DisplayTree( node *); int isOperator(char ); struct Basic_tree { char data; node *lptr; node *rptr; }*first; struct opr { char op_name; node *t; }oprate[50]; char current_operators[5]={'+','*','(',')','['}; char OperatorsInStack[5]={'+','*','(',')',']'}; void main() { char exp[10]; int myVariable=0,row=0,col=0; node *temp; // clrscr(); printf("Enter Exp : "); scanf("%s",exp); T4Tutorials_value(); while(exp[myVariable] != '\0') { if(myVariable==0) { tos++; oprate[tos].op_name = exp[tos]; } else { if(isOperator(exp[myVariable]) == -1) { oprate[tos].t = (node*) malloc (sizeof(node)); oprate[tos].t->data = exp[myVariable]; oprate[tos].t->lptr = '\0'; oprate[tos].t->rptr = '\0'; } else { row = Operator_Position_Finder(oprate[tos].op_name); col = Operator_Position_Finder(exp[myVariable]); if(T4Tutorials[row][col] == 0) { tos++; oprate[tos].op_name = exp[myVariable]; } elseif(T4Tutorials[row][col] == 1) { temp = (node*) malloc (sizeof(node)); temp->data = oprate[tos].op_name; temp->lptr = (oprate[tos-1].t); temp->rptr = (oprate[tos].t); tos--; oprate[tos].t = temp; myVariable--; } elseif(T4Tutorials[row][col] == 2) { //temp = (node*) malloc (sizeof(node)); temp = oprate[tos].t; tos--; oprate[tos].t = temp; } elseif(T4Tutorials[row][col] == 3) { printf("\nExpression is Invalid...\n"); printf("%c %c can not occur simultaneously\n",oprate[tos].op_name,exp[myVariable]); break; } } } myVariable++; } printf("show tree \n\n\n"); DisplayTree(oprate[tos].t); printf("Over"); getch(); getch(); } int isOperator(char c) { int i=0; for(i=0;i<5;i++) { if (c==current_operators[i] || c==OperatorsInStack[i]) break; } if(i==5) return (-1); elsereturn i; } int Operator_Position_Finder(char c) { int i; for(i=0;i<5;i++) { if (c==current_operators[i] || c==OperatorsInStack[i]) break; } return i; } void DisplayTree(node *start) { if(start->lptr != NULL) DisplayTree(start->lptr); if(start->rptr != NULL) DisplayTree(start->rptr); printf("%c \n",start->data); } void T4Tutorials_value(void) { int i,j; printf("OPERATOR PRECEDENCE Matrix\n"); printf("===========================\n "); for(i=0; i<5; i++) { printf("%c ",OperatorsInStack[i]); } printf("\n"); for(i=0;i<5;i++) { printf("%c ",current_operators[i]); for(j=0;j<5;j++) { if(T4Tutorials[i][j] == 0) printf("< "); elseif(T4Tutorials[i][j] == 1) printf("> "); elseif(T4Tutorials[i][j] == 2) printf("= "); elseif(T4Tutorials[i][j] == 3) printf(" "); } printf("\n"); } } |
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