Stack Operations using C Language

Implement stack as an abstract data type (ADT) using linked list.

Use this ADT for

•  infix to prefix conversion
• infix to post fix conversion
• evaluation of post fix expression

 #include  
 #include  
 #include  
 #include  
 #include  
 typedef struct stack  
 {  
 char data;  
 struct stack * link;  
 }stack;  
 typedef struct eval  
 {  
 float data;  
 struct eval * link;  
 }eval;  
 typedef struct val  
 {  
 char data;  
 float value;  
 struct val * link;  
 }val;  
 int pinppost(char);  
 int pstppost(char);  
 int pinppre(char);  
 int pstppre(char);  
 float posteval(char []);  
 float preeval(char []);  
 void create(char []);  
 void postfix(char [],char []);  
 void prefix(char [],char []);  
 void display(char []);  
 void main()  
 {  
 int ch;  
 float j;  
 char str[50],str1[50],str2[50];  
 float dummy;  
 &dummy;  
 str[0]=NULL;  
 str1[0]=NULL;  
 str2[0]=NULL;  
 clrscr();  
 do  
 {  
 clrscr();  
 printf("\n\t\tOPERATION ON STACK\n\t\t1.INFIX EXPRESSION\n\t\t2.INFIX TO PREFIX\n\t\t3.INFIX TO POSTFIX\n\t\t4.EVALUATION FOR PREFIX\n\t\t5.EVALUATION FOR POSTFIX\n\t\t6.EXIT");  
 printf("\n\t\tENTER UR CHOICE");  
 flushall();  
 scanf("%d",&ch);  
 switch(ch)  
 {  
 case 1:  
 printf("\n\t\tINFIX EXPRESSION:");  
 create(str);  
 display(str);  
 break;  
 case 2:  
 if(str[0]==NULL)  
 printf("enter input first");  
 else  
 {  
 printf("\n\t\tINFIX TO PREFIX :");  
 prefix(str,str2);  
 printf("\nINFIX EXPRESSION IS:");  
 display(str);  
 printf("\nPREFIX EXPRESSION IS:");  
 display(str2);  
 }  
 getch();  
 break;  
 case 3: if(str[0]==NULL)  
 printf("enter input first");  
 else  
 {  
 printf("\n\t\tINFIX TO POSTFIX EXPRESSION");  
 postfix(str,str1);  
 printf("\nINFIX EXPRESSION IS:");  
 display(str);  
 printf("\nPOSTFIX EXPRESSION IS:");  
 display(str1);  
 }  
 getch();  
 break;  
 case 4: if(str[0]==NULL||str2[0]==NULL)  
 printf("either you havnt given input or you havnt done conversion,first do that part ");  
 else  
 {  
 printf("\n\t\tEVALUATION ON PREFIX EXPRESSION");  
 j=preeval(str2);  
 printf("\nVALUE EVALUATED IS:%f",j);  
 }  
 getch();  
 break;  
 case 5: if(str[0]==NULL||str1[0]==NULL)  
 printf("either you havnt given input or you havnt done conversion,first do that part ");  
 else  
 {  
 printf("\n\t\tEVALUATION ON POSTFIX EXPRESSION");  
 j=posteval(str1);  
 printf("\nVALUE EVALUATED IS:%f",j);  
 }  
 getch();  
 break;  
 case 6:  
 printf("\n\t\tEXIT");  
 break;  
 }  
 }while(ch!=6);  
 }  
 void create(char str[])  
 {  
 int rank=0,i=0,j=0,k,m,l;  
 while(1)  
 {  
 str[i]=getche();  
 i++;  
 if(str[i-1]=='\r')  
 {  
 if(rank!=1||j!=0||i<=2)  
 {  
 printf("\ninvalid exprexion,enter from starting");  
 j=0;  
 rank=0;  
 i=0;  
 }  
 else  
 break;  
 }  
 else if(str[i-1]=='(')  
 if(rank==1)  
 {  
 printf("\ninvalid exprexion,enter from starting");  
 i=0;  
 j=0;  
 rank=0;  
 }  
 else  
 j++;  
 else if(str[i-1]==')')  
 if(rank==0)  
 {  
 printf("\ninvalid exprexion,enter from starting");  
 i=0;  
 j=0;  
 rank=0;  
 }  
 else  
 j--;  
 else if(str[i-1]=='+'||str[i-1]=='-'||str[i-1]=='*'|| str[i-1]=='^'||str[i-1]=='/')  
 rank=rank-1;  
 else if((str[i-1]>=48&&str[i-1]<=57)||(str[i-1]>=65&&str[i-1]<=90)||(str[i-1]>=97&&str[i-1]<=122))  
 rank=rank+1;  
 else if(str[i-1]!=')'&&str[i-1]!='(')  
 {  
 printf("\ninvalid entry,enter from starting");  
 i=0;  
 j=0;  
 rank=0;  
 }  
 if((rank!=1&&rank!=0)||j<0)  
 {  
 printf("\ninvalid exprexion,enter from starting");  
 i=0;  
 j=0;  
 rank=0;  
 }  
 }  
 str[i]=NULL;  
 }  
 void display(char str[])  
 {  
 int i=0;  
 while(str[i]!=NULL)  
 {  
 printf("%c",str[i]);  
 i++;  
 }  
 getch();  
 }  
 void prefix(char str[],char str2[])  
 {  
 int i,l,j;  
 stack *nw,*top,*top1=NULL;  
 l=strlen(str);  
 i=l-1;  
 for(j=l;j>0;j--)  
 str[j]=str[j-1];  
 str[j]='#';  
 nw=(stack *)malloc(sizeof(stack));  
 nw->data='#';  
 top=nw;  
 while(1)  
 {  
 while(pinppre(str[i])<pstppre(top->data))  
 {  
 nw=(stack *)malloc(sizeof(stack));  
 nw->data=top->data;  
 nw->link=top1;  
 top1=nw;  
 nw=top;  
 top=top->link;  
 free(nw);  
 }  
 if(pinppre(str[i])==pstppre(top->data))  
 {  
 if(top->data=='#')  
 break;  
 nw=top;  
 top=top->link;  
 free(nw);  
 i--;  
 }  
 else  
 {  
 nw=(stack *)malloc(sizeof(stack));  
 nw->data=str[i--];  
 nw->link=top;  
 top=nw;  
 }  
 }  
 for(j=0;j<l;j++) <br=""> {  
 str[j]=str[j+1];  
 }  
 str[l]=NULL;  
 j=0;  
 while(top1!=NULL)  
 {  
 str2[j]=top1->data;  
 nw=top1;  
 top1=top1->link;  
 free(nw);  
 j++;  
 }  
 str2[j]=NULL;  
 }  
 void postfix(char str[],char str1[])  
 {  
 int l,i,j;  
 stack *nw,*top;  
 i=j=0;  
 l=strlen(str);  
 str[l-1]='#';  
 nw=(stack *)malloc(sizeof(stack));  
 nw->data='#';  
 top=nw;  
 while(1)  
 {  
 while(pinppost(str[i])<pstppost(top->data))  
 {  
 str1[j++]=top->data;  
 nw=top;  
 top=top->link;  
 free(nw);  
 }  
 if(pinppost(str[i])==pstppost(top->data))  
 {  
 if(top->data=='#')  
 break;  
 nw=top;  
 top=top->link;  
 free(nw);  
 i++;  
 }  
 else  
 {  
 nw=(stack *)malloc(sizeof(stack));  
 nw->data=str[i++];  
 nw->link=top;  
 top=nw;  
 }  
 }  
 str[l-1]=NULL;  
 str1[j]=NULL;  
 }  
 int pinppost(char c)  
 {  
 switch(c)  
 {  
 case '#': return(-1);  
 case '*':  
 case '/': return(3);  
 case '+':  
 case '-': return(1);  
 case '^': return(6);  
 case '(': return(8);  
 case ')': return(0);  
 }  
 return(7);  
 }  
 int pstppost(char c)  
 {  
 switch(c)  
 {  
 case '#': return(-1);  
 case '*':  
 case '/': return(4);  
 case '+':  
 case '-': return(2);  
 case '^': return(5);  
 case '(': return(0);  
 }  
 return(7);  
 }  
 int pinppre(char c)  
 {  
 switch(c)  
 {  
 case '#': return(-1);  
 case '*':  
 case '/': return(4);  
 case '+':  
 case '-': return(2);  
 case '^': return(5);  
 case '(': return(0);  
 case ')': return(8);  
 }  
 return(7);  
 }  
 int pstppre(char c)  
 {  
 switch(c)  
 {  
 case '#': return(-1);  
 case '*':  
 case '/': return(3);  
 case '+':  
 case '-': return(1);  
 case '^': return(6);  
 case ')': return(0);  
 }  
 return(7);  
 }  
 float posteval(char str1[])  
 {  
 val *nw,*t,*top=NULL;  
 eval *nw1,*top1=NULL;  
 int i;  
 float opr1;  
 char op;  
 i=0;  
 for(i=0;str1[i]!=NULL;i++)  
 {  
 if(str1[i]!='+'&&str1[i]!='-'&&str1[i]!='*'&& str1[i]!='^'&&str1[i]!='/')  
 {  
 nw=top;  
 while(nw!=NULL)  
 {  
 if(str1[i]==nw->data)  
 break;  
 nw=nw->link;  
 }  
 if(nw==NULL)  
 {  
 nw=(val *)malloc(sizeof(val));  
 nw->data=str1[i];  
 printf("ENTER THE VALUE OF %c:",str1[i]);  
 scanf("%f",&(nw->value));  
 nw->link=top;  
 top=nw;  
 }  
 nw1=(eval *)malloc(sizeof(eval));  
 nw1->data=nw->value;  
 nw1->link=top1;  
 top1=nw1;  
 }  
 else  
 {  
 op=str1[i];  
 opr1=top1->data;  
 nw1=top1;  
 top1=top1->link;  
 free(nw1);  
 switch(op)  
 {  
 case '*':opr1=top1->data*opr1;  
 break;  
 case '/':opr1=top1->data/opr1;  
 break;  
 case '+':opr1=top1->data+opr1;  
 break;  
 case '-':opr1=top1->data-opr1;  
 break;  
 case '^':opr1=pow(top1->data,opr1);  
 break;  
 }  
 top1->data=opr1;  
 }  
 }  
 opr1=top1->data;  
 free(top1);  
 return(opr1);  
 }  
 float preeval(char str[])  
 {  
 val *nw,*t,*top=NULL;  
 eval *nw1,*top1=NULL;  
 int i,n;  
 float opr1,opr2;  
 char op;  
 i=0;  
 for(i=0;str[i]!=NULL;i++)  
 {  
 if(str[i]!='+'&&str[i]!='-'&&str[i]!='*'&& str[i]!='^'&&str[i]!='/')  
 {  
 nw=top;  
 while(nw!=NULL)  
 {  
 if(str[i]==nw->data)  
 break;  
 nw=nw->link;  
 }  
 if(nw==NULL)  
 {  
 nw=(val *)malloc(sizeof(val));  
 nw->data=str[i];  
 printf("ENTER THE VALUE OF %c:",str[i]);  
 scanf("%f",&(nw->value));  
 nw->link=top;  
 top=nw;  
 }  
 opr1=nw->value;  
 while(1)  
 {  
 if(top1==NULL||top1->data=='+'||top1->data=='-'||top1->data=='*'||top1->data=='/'||top1->data=='^')  
 break;  
 opr2=top1->data;  
 nw1=top1;  
 top1=top1->link;  
 free(nw1);  
 op=(char)top1->data;  
 nw1=top1;  
 top1=top1->link;  
 free(nw1);  
 switch(op)  
 {  
 case '*':opr1=opr2*opr1;  
 break;  
 case '/':opr1=opr2/opr1;  
 break;  
 case '+':opr1=opr2+opr1;  
 break;  
 case '-':opr1=opr2-opr1;  
 break;  
 case '^':opr1=pow(opr2,opr1);  
 break;  
 }  
 }  
 nw1=(eval*)malloc(sizeof(eval));  
 nw1->data=opr1;  
 nw1->link=top1;  
 top1=nw1;  
 }  
 else  
 {  
 nw1=(eval*)malloc(sizeof(eval));  
 nw1->data=(float)str[i];  
 nw1->link=top1;  
 top1=nw1;  
 }  
 }  
 opr1=top1->data;  
 free(top1);  
 return(opr1);  
 }