some changes

05_Arrays/3_PrintingArrays.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+int main() {
+    // Declare and initialize an array
+    int arr[] = {1, 2, 3, 4, 5};
+    int size = sizeof(arr) / sizeof(arr[0]); // Calculate the size of the array
+
+
+    printf("Array elements: ");
+    for (int i = 0; i < size; i++) {
+        printf("%d ", arr[i]);
+    }
+    printf("\n");
+
+    return 0;
+}

infix_postfix.c

@@ -0,0 +1,175 @@
+#include<stdio.h>
+#include<stdlib.h>      /* for exit() */
+#include<ctype.h>     /* for isdigit(char ) */
+#include<string.h>
+
+#define SIZE 100
+
+
+
+char stack[SIZE];
+int top = -1;
+
+
+
+void push(char item)
+{
+	if(top >= SIZE-1)
+	{
+		printf("\nStack Overflow.");
+	}
+	else
+	{
+		top = top+1;
+		stack[top] = item;
+	}
+}
+
+
+char pop()
+{
+	char item ;
+
+	if(top <0)
+	{
+		printf("stack under flow: invalid infix expression");
+		getchar();
+
+		exit(1);
+	}
+	else
+	{
+		item = stack[top];
+		top = top-1;
+		return(item);
+	}
+}
+
+
+int is_operator(char symbol)
+{
+	if(symbol == '^' || symbol == '*' || symbol == '/' || symbol == '+' || symbol =='-')
+	{
+		return 1;
+	}
+	else
+	{
+	return 0;
+	}
+}
+
+
+int precedence(char symbol)
+{
+	if(symbol == '^')/* exponent operator, highest precedence*/
+	{
+		return(3);
+	}
+	else if(symbol == '*' || symbol == '/')
+	{
+		return(2);
+	}
+	else if(symbol == '+' || symbol == '-')          /* lowest precedence */
+	{
+		return(1);
+	}
+	else
+	{
+		return(0);
+	}
+}
+
+void InfixToPostfix(char infix_exp[], char postfix_exp[])
+{
+	int i, j;
+	char item;
+	char x;
+
+	push('(');                               /* push '(' onto stack */
+	strcat(infix_exp,")");                  /* add ')' to infix expression */
+
+	i=0;
+	j=0;
+	item=infix_exp[i];         /* initialize before loop*/
+
+	while(item != '\0')        /* run loop till end of infix expression */
+	{
+		if(item == '(')
+		{
+			push(item);
+		}
+		else if( isdigit(item) || isalpha(item))
+		{
+			postfix_exp[j] = item;              /* add operand symbol to postfix expr */
+			j++;
+		}
+		else if(is_operator(item) == 1)        /* means symbol is operator */
+		{
+			x=pop();
+			while(is_operator(x) == 1 && precedence(x)>= precedence(item))
+			{
+				postfix_exp[j] = x;                  /* so pop all higher precendence operator and */
+				j++;
+				x = pop();                       /* add them to postfix expresion */
+			}
+			push(x);
+
+			push(item);                 /* push current oprerator symbol onto stack */
+		}
+		else if(item == ')')         /* if current symbol is ')' then */
+		{
+			x = pop();                   /* pop and keep popping until */
+			while(x != '(')                /* '(' encounterd */
+			{
+				postfix_exp[j] = x;
+				j++;
+				x = pop();
+			}
+		}
+		else
+		{
+			printf("\nInvalid infix Expression.\n");        /* the it is illegeal  symbol */
+			getchar();
+			exit(1);
+		}
+		i++;
+
+
+		item = infix_exp[i]; /* go to next symbol of infix expression */
+	}
+
+
+	if(top>0)
+	{
+		printf("\nInvalid infix Expression.\n");        /* the it is illegeal  symbol */
+		getchar();
+		exit(1);
+	}
+	if(top>0)
+	{
+		printf("\nInvalid infix Expression.\n");        /* the it is illegeal  symbol */
+		getchar();
+		exit(1);
+	}
+
+
+	postfix_exp[j] = '\0'; /* add sentinel for puts() fucntion */
+
+}
+
+/* main function begins */
+int main()
+{
+	char infix[SIZE], postfix[SIZE];         /* declare infix string and postfix string */
+
+
+	printf("ASSUMPTION: The infix expression contains single letter variables and single digit constants only.\n");
+	printf("\nEnter Infix expression : ");
+	gets(infix);
+
+	InfixToPostfix(infix,postfix);                   /* call to convert */
+	printf("Postfix Expression: ");
+	puts(postfix);                     /* print postfix expression */
+
+	return 0;
+}