Created postfix to infix converter

conversions/postfix_to_infix.c

@@ -0,0 +1,130 @@
+/**
+ * Supported operations- '+', '-', '/', '*', '%'
+ *  @author [Kavya Shah](https://github.com/Kavyashah26)
+ * 
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+struct Stack
+{
+    int top;
+    unsigned capacity;
+    char** array;
+};
+
+// createStack creates a stack with given capacity
+struct Stack* createStack(unsigned capacity)
+{
+    struct Stack* stack = (struct Stack*)malloc(sizeof(struct Stack));
+    stack->top = -1;
+    stack->capacity = capacity;
+    stack->array = (char**)malloc(stack->capacity * sizeof(char*));
+    return stack;
+}
+
+// isEmpty checks if the stack is empty
+int isEmpty(struct Stack* stack) { return stack->top == -1; }
+
+// push pushes an element to the stack
+void push(struct Stack* stack, char* item)
+{
+    stack->array[++stack->top] = item;
+}
+
+// pop pops an element from the stack
+char* pop(struct Stack* stack)
+{
+    if (!isEmpty(stack))
+        return stack->array[stack->top--];
+    return NULL;
+}
+
+// isOperand checks if a character is an operand
+int isOperand(char ch)
+{
+    return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z');
+}
+
+//  isOperator checks if a character is an operator
+int isOperator(char ch)
+{
+    return ch == '+' || ch == '*' || ch == '-' || ch == '/' || ch == '^';
+}
+
+// postfixToInfix  converts postfix expression to infix
+//returns correct infix operation if all the conditions are passed
+char* postfixToInfix(char* postfix)
+{
+    struct Stack* stack = createStack(strlen(postfix));
+
+    int operandCount = 0;
+    int operatorCount = 0;
+
+    for (int i = 0; postfix[i]; ++i)
+    {
+        if (isOperand(postfix[i]))
+        {
+            char* operand = (char*)malloc(2 * sizeof(char));
+            operand[0] = postfix[i];
+            operand[1] = '\0';
+            push(stack, operand);
+            operandCount++;
+        }
+        else if (isOperator(postfix[i]))
+        {
+            char* op2 = pop(stack);
+            char* op1 = pop(stack);
+            if (op1 == NULL || op2 == NULL)
+            {
+                assert(0 && "Invalid postfix expression. Not enough operands.");
+            }
+            char* temp =
+                (char*)malloc((strlen(op1) + strlen(op2) + 4) * sizeof(char));
+            sprintf(temp, "(%s%c%s)", op1, postfix[i], op2);
+            push(stack, temp);
+            operatorCount++;
+        }
+        else if (postfix[i] != '(' && postfix[i] != ')')
+        {
+            assert(0 && "Invalid character in postfix expression");
+        }
+    }
+
+    if (operandCount - operatorCount != 1)
+    {
+        assert(0 && "Operand count and operator count do not match");
+    }
+
+    return stack->array[0];
+}
+static void test(){
+    char* postfix[] = {
+        "abc^^de-*fg^h^+i-",  
+        "ab+",                 
+        "ab+c*",               
+    };
+
+    char* ans[] = {
+        "((((a^(b^c))*(d-e))+((f^g)^h))-i)",  
+        "(a+b)",                                
+        "((a+b)*c)",                           
+    };
+    char* result;
+
+        for (int i = 0; i < sizeof(ans) / sizeof(ans[0]); i++){
+        result=postfixToInfix(postfix[i]);
+        assert(strcmp(result,ans[i])==0);
+        printf("Testcase %d passed\n",i+1);
+    }
+    free(result); // Free memory allocated for the result
+}
+int main()
+{
+    test();
+    printf("All test cases passed");
+    return 0;
+}