add code for Infix to Prefix

conversions/infix_to_prefix.c

@@ -0,0 +1,117 @@
+#include <stdio.h>
+#include <string.h>
+
+// Define a stack structure to hold characters
+struct Stack {
+    char arr[10];
+    int tos; // Top of stack
+};
+
+// Function to push a character onto the stack
+void push(struct Stack *p, char ch) {
+    // Check for stack overflow
+    if (p->tos == 9) {
+        printf("Stack Overflow!");
+        return;
+    }
+
+    p->tos += 1; // Increment top of stack
+    p->arr[p->tos] = ch; // Store character in the stack
+}
+
+// Function to pop a character from the stack
+char pop(struct Stack *p) {
+    char x;
+
+    // Check for stack underflow
+    if (p->tos == -1) {
+        printf("Stack Underflow!");
+        return '\0';
+    }
+
+    x = p->arr[p->tos]; // Get character from the top of the stack
+    p->tos -= 1; // Decrement top of stack
+
+    return x;
+}
+
+// Function to check if a character is an operand
+int isOperand(char ch) {
+    return (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z');
+}
+
+// Function to check if the stack is empty
+int isEmpty(struct Stack s) {
+    return s.tos == -1;
+}
+
+// Function to determine operator precedence
+int getPrecedence(char op1, char op2) {
+    if ((op1 == '*' || op1 == '/' || op1 == '%') && (op2 == '+' || op2 == '-')) {
+        return 1;
+    }
+    return 0;
+}
+
+// Function to convert infix expression to prefix expression
+void infixToPrefix(char infix[], char prefix[]) {
+    struct Stack s; // Initialize a stack
+    s.tos = -1; // Initialize top of stack
+
+    int i, j = 0;
+    char ch, temp;
+    int len = strlen(infix);
+
+    // Scan the infix expression from right to left
+    for (i = len - 1; i >= 0; i--) {
+        ch = infix[i];
+
+        if (isOperand(ch)) {
+            prefix[j] = ch; // Add operand to prefix expression
+            j++;
+        } else {
+            if (ch == ')') {
+                push(&s, ch); // Push ')' onto the stack
+            } else if (ch == '(') {
+                while ((temp = pop(&s)) != ')') {
+                    prefix[j] = temp; // Pop and add operators to prefix until '(' is encountered
+                    j++;
+                }
+            } else {
+                while (!isEmpty(s) && getPrecedence(ch, s.arr[s.tos])) {
+                    temp = pop(&s);
+                    prefix[j] = temp; // Pop and add operators to prefix based on precedence
+                    j++;
+                }
+                push(&s, ch); // Push the current operator onto the stack
+            }
+        }
+    }
+
+    // Pop any remaining operators from the stack and add to prefix
+    while (!isEmpty(s)) {
+        temp = pop(&s);
+        prefix[j] = temp;
+        j++;
+    }
+
+    prefix[j] = '\0';
+
+    // Reverse the prefix expression to get the correct order
+    strrev(prefix);
+}
+
+
+
+int main() {
+    char infix[20], prefix[20];
+
+    printf("Enter infix expression: ");
+    scanf("%s", infix);
+
+    infixToPrefix(infix, prefix);
+
+    printf("Prefix expression is %s\n", prefix);
+
+    return 0;
+}