#define SIZE 5            /* Size of Queue */
int f=0,r=-1;       /* Global declarations */
typedef struct PRQ
{
    int ele;
    int pr;
}PriorityQ;

PriorityQ PQ[SIZE];

PQinsert(int elem, int pre)
{
    int i;       /* Function for Insert operation */
    if( Qfull()) printf("\n\n Overflow!!!!\n\n");
    else
    {
        i=r;
        ++r;
        while(PQ[i].pr <= pre && i >= 0) /* Find location for new elem */
        {
            PQ[i+1]=PQ[i];
            i--;
        }
        PQ[i+1].ele=elem;
        PQ[i+1].pr=pre;
    }
}

PriorityQ PQdelete()
{                      /* Function for Delete operation */
    PriorityQ p;
    if(Qempty()){ printf("\n\nUnderflow!!!!\n\n");
    p.ele=-1;p.pr=-1;
    return(p); }
    else
    {
        p=PQ[f];
        f=f+1;
        return(p);
    }
}
int Qfull()
{                     /* Function to Check Queue Full */
    if(r==SIZE-1) return 1;
    return 0;
}

int Qempty()
{                    /* Function to Check Queue Empty */
    if(f > r) return 1;
    return 0;
}

display()
{                  /* Function to display status of Queue */
    int i;
    if(Qempty()) printf(" \n Empty Queue\n");
    else
    {
        printf("Front->");
        for(i=f;i<=r;i++)
            printf("[%d,%d] ",PQ[i].ele,PQ[i].pr);
        printf("<-Rear");
    }
}

main()
{                         /* Main Program */
    int opn;
    PriorityQ p;
    do
    {
        clrscr();
        printf("\n ### Priority Queue Operations(DSC order) ### \n\n");
        printf("\n Press 1-Insert, 2-Delete,3-Display,4-Exit\n");
        printf("\n Your option ? ");
        scanf("%d",&opn);
        switch(opn)
        {
        case 1: printf("\n\nRead the element and its Priority?");
            scanf("%d%d",&p.ele,&p.pr);
            PQinsert(p.ele,p.pr); break;
        case 2: p=PQdelete();
            if( p.ele != -1)
                printf("\n\nDeleted Element is %d \n",p.ele);
            break;
        case 3: printf("\n\nStatus of Queue\n\n");
            display(); break;
        case 4: printf("\n\n Terminating \n\n"); break;
        default: printf("\n\nInvalid Option !!! Try Again !! \n\n");
            break;
        }
        printf("\n\n\n\n  Press a Key to Continue . . . ");
        getch();
    }while(opn != 4);
}

The post C Program for Simple DSC order Priority QUEUE Implementation using Structure first appeared on Student Projects.

#include 
#include 
char opnds[50][80],oprs[50];
int  topr=-1,topd=-1;
pushd(char *opnd)
{
    strcpy(opnds[++topd],opnd);
}
char *popd()
{
    return(opnds[topd--]);
}

pushr(char opr)
{
    oprs[++topr]=opr;
}
char popr()
{
    return(oprs[topr--]);
}
int empty(int t)
{
    if( t == 0) return(1);
    return(0);
}

main()
{
    char prfx[50],ch,str[50],opnd1[50],opnd2[50],opr[2];
    int i=0,k=0,opndcnt=0;
    gets(prfx);
    printf(" Given Prefix Expression : %s\n",prfx);
    while( (ch=prfx[i++]) != '\0')
    {
        if(isalnum(ch))
        {
            str[0]=ch; str[1]='\0';
            pushd(str); opndcnt++;
            if(opndcnt >= 2)
            {
                strcpy(opnd2,popd());
                strcpy(opnd1,popd());
                strcpy(str,"(");
                strcat(str,opnd1);
                ch=popr();
                opr[0]=ch;opr[1]='\0';
                strcat(str,opr);
                strcat(str,opnd2);
                strcat(str,")");
                pushd(str);
                opndcnt-=1;
            }
        }
        else
        {
            pushr(ch);
            if(opndcnt==1)opndcnt=0;  /* operator followed by single operand*/
        }
    }
    if(!empty(topd))
    {
        strcpy(opnd2,popd());
        strcpy(opnd1,popd());
        strcpy(str,"(");
        strcat(str,opnd1);
        ch=popr();
        opr[0]=ch;opr[1]='\0';
        strcat(str,opr);
        strcat(str,opnd2);
        strcat(str,")");
        pushd(str);
    }
    printf(" Infix Expression: ");
    puts(opnds[topd]);
}

The post C Program to convert Prefix Expression into INFIX first appeared on Student Projects.

#define SIZE 50            /* Size of Stack */
#include
#include 
char s[SIZE];
int top=-1;       /* Global declarations */

push(char elem)
{                       /* Function for PUSH operation */
    s[++top]=elem;
}

char pop()
{                      /* Function for POP operation */
    return(s[top--]);
}

int pr(char elem)
{                 /* Function for precedence */
    switch(elem)
    {
    case '#': return 0;
    case ')': return 1;
    case '+':
    case '-': return 2;
    case '*':
    case '/': return 3;
    }
}

main()
{                         /* Main Program */
    char infx[50],prfx[50],ch,elem;
    int i=0,k=0;
    printf("\n\nRead the Infix Expression ? ");
    scanf("%s",infx);
    push('#');
    strrev(infx);
    while( (ch=infx[i++]) != '\0')
    {
        if( ch == ')') push(ch);
        else
            if(isalnum(ch)) prfx[k++]=ch;
            else
                if( ch == '(')
                {
                    while( s[top] != ')')
                        prfx[k++]=pop();
                    elem=pop(); /* Remove ) */
                }
                else
                {       /* Operator */
                    while( pr(s[top]) >= pr(ch) )
                        prfx[k++]=pop();
                    push(ch);
                }
    }
    while( s[top] != '#')     /* Pop from stack till empty */
        prfx[k++]=pop();
    prfx[k]='\0';          /* Make prfx as valid string */
    strrev(prfx);
    strrev(infx);
    printf("\n\nGiven Infix Expn: %s  Prefix Expn: %s\n",infx,prfx);
}

The post C Program for Infix to Prefix Conversion first appeared on Student Projects.