Data_Structures/infixToPostfixUsignStack.c at master · pchintan243/Data_Structures · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
struct stack
{
    int size;
    int top;
    char *arr;
};

char stacktop(struct stack *ptr)
{
    return ptr->arr[ptr->top];
}

int isEmpty(struct stack *ptr)
{
    if (ptr->top == -1)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}

int isFull(struct stack *ptr)
{
    if (ptr->top == ptr->size - 1)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}

void push(struct stack *ptr, char data)
{
    if (isFull(ptr))
    {
        printf("Stack is overflow..!!\n");
        printf("So you cannot push %d to the stack..!!\n", data);
        return;
    }
    else
    {
        ptr->top++;
        ptr->arr[ptr->top] = data;
        // printf("%d ", ptr->arr[ptr->top]);
    }
}
char pop(struct stack *ptr)
{
    if (isEmpty(ptr))
    {
        printf("Stack is Underflow..!!\n");
        return -1;
    }
    else
    {
        char data = ptr->arr[ptr->top];
        ptr->top--;
        return data;
    }
}

int peek(struct stack *ptr, int i)
{
    if (ptr->top - i + 1 < 0)
    {
        printf("Not a valid position..!!\n");
        return -1;
    }
    else
    {
        return ptr->arr[ptr->top - i + 1];
    }
}

int precedence(char ch)
{
    if (ch == '*' || ch == '/')
    {
        return 3;
    }
    else if(ch == '+' || ch == '-') {
        return 2;
    }
    else {
        return 0;
    }
}


int isOperator(char ch) {
    if(ch == '+' || ch == '-' || ch == '*' || ch == '/') {
        return 1;
    }
    else {
        return 0;
    }
}
char *infixToPostfix(char *infix)
{
    struct stack *sp = (struct stack *) malloc(sizeof(struct stack));
    sp->size = 100;
    sp->top = -1;
    sp->arr = (char *)malloc(sp->size * sizeof(char));
    char *postfix = (char *)malloc((strlen(infix) + 1) * sizeof(char));
    int i = 0; // Track infix traversal
    int j = 0; // Track postfix traversal

    while (infix[i] != '\0')
    {
        if (!isOperator(infix[i]))
        {
            postfix[j] = infix[i];
            j++;
            i++;
        }
        else
        {
            if (precedence(infix[i]) > precedence(stacktop(sp)))
            {
                push(sp, infix[i]);
                i++;
            }
            else
            {
                postfix[j] = pop(sp);
                j++;
            }
        }
    }
    while (!isEmpty(sp))
    {
        postfix[j] = pop(sp);
        j++;
    }
    postfix[j] = '\0';
    return postfix;
}
int main()
{
    char *infix = "x-y/z-k*d";
    printf("Postfix is %s", infixToPostfix(infix));
    return 0;
}