#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
// Function to return precedence of operators
int prec(char c) {
if (c == '^')
return 3;
else if (c == '/' || c == '*')
return 2;
else if (c == '+' || c == '-')
return 1;
else
return -1;
}
// Function to return associativity of operators
char associativity(char c) {
if (c == '^')
return 'R';
return 'L'; // Default to left-associative
}
// Function to convert infix expression to postfix expression
void infixToPostfix(char s[], char result[]) {
int resultIndex = 0;
int len = strlen(s);
char stack[1000];
int stackIndex = -1;
for (int i = 0; i < len; i++) {
char c = s[i];
// If the scanned character is an operand, add it to the output string.
if (isalnum(c)) {
result[resultIndex++] = c;
}
// If the scanned character is an ‘(‘, push it to the stack.
else if (c == '(') {
stack[++stackIndex] = c;
}
// If the scanned character is an ‘)’, pop and add to the output string from the stack
// until an ‘(‘ is encountered.
else if (c == ')') {
while (stackIndex >= 0 && stack[stackIndex] != '(') {
result[resultIndex++] = stack[stackIndex--];
}
stackIndex--; // Pop '('
}
// If an operator is scanned
else {
while (stackIndex >= 0 && (prec(s[i]) < prec(stack[stackIndex]) ||
(prec(s[i]) == prec(stack[stackIndex]) &&
associativity(s[i]) == 'L'))) {
result[resultIndex++] = stack[stackIndex--];
}
stack[++stackIndex] = c;
}
}
// Pop all the remaining elements from the stack
while (stackIndex >= 0) {
result[resultIndex++] = stack[stackIndex--];
}
result[resultIndex] = '\0';
}
// Function to evaluate postfix expression
int evaluatePostfix(char postfix[]) {
int len = strlen(postfix);
int stack[1000];
int top = -1;
for (int i = 0; i < len; i++) {
char c = postfix[i];
if (isdigit(c)) {
stack[++top] = c - '0'; // Convert char to int
} else {
int operand2 = stack[top--];
int operand1 = stack[top--];
switch (c) {
case '+':
stack[++top] = operand1 + operand2;
break;
case '-':
stack[++top] = operand1 - operand2;
break;
case '*':
stack[++top] = operand1 * operand2;
break;
case '/':
stack[++top] = operand1 / operand2;
break;
case '^':
stack[++top] = (int)pow(operand1, operand2);
break;
}
}
}
return stack[top];
}
int main() {
char infix[1000];
char postfix[1000];
// Taking input from the user
printf("Enter an infix expression: ");
scanf("%s", infix);
// Convert infix to postfix
infixToPostfix(infix, postfix);
printf("Postfix expression: %s\n", postfix);
// Evaluate postfix expression
int result = evaluatePostfix(postfix);
printf("Result: %d\n", result);
return 0;
}
Write, Run & Share C Language code online using OneCompiler's C online compiler for free. It's one of the robust, feature-rich online compilers for C language, running the latest C version which is C18. Getting started with the OneCompiler's C editor is really simple and pretty fast. The editor shows sample boilerplate code when you choose language as 'C' and start coding!
OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.
#include <stdio.h>
int main()
{
char name[50];
printf("Enter name:");
scanf("%s", name);
printf("Hello %s \n" , name );
return 0;
}
C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.
When ever you want to perform a set of operations based on a condition if-else is used.
if(conditional-expression) {
// code
} else {
// code
}
You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.
Switch is an alternative to if-else-if ladder.
switch(conditional-expression) {
case value1:
// code
break; // optional
case value2:
// code
break; // optional
...
default:
// code to be executed when all the above cases are not matched;
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
// code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while(condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.
data-type array-name[size];
data-type array-name[size][size];
Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
Two types of functions are present in C
Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,
User defined functions are the ones which are written by the programmer based on the requirement.
return_type function_name(parameters);
function_name (parameters)
return_type function_name(parameters) {
//code
}