#include <stdio.h>
#include <stdint.h>

typedef union f2b f2b;
union f2b {
  float fn; //  float value
  uint8_t fb[sizeof(float)];  //  fn as bytes
  uint32_t ib;  //  just for printf
};

uint8_t eeprom[sizeof(float) * 2];  //  dummy save area for read/write

//  dummy EEPROM.write()
void eeprom_write(size_t offset, uint8_t byte) {
  printf("offset: %2zu, value: %02x\n", offset, byte);
  eeprom[offset] = byte;
  return;
}

//  dummy EEPROM.read()
uint8_t eeprom_read(size_t offset) {
  uint8_t byte = eeprom[offset];
  printf("offset: %2zu, value: %02x\n", offset, byte);
  return byte;
}

int main(int argc, char const * argv[]) {
  size_t of0 = 0 * sizeof(float);
  size_t of1 = 1 * sizeof(float);

  float nr = 24.6;
  float ns = 26.0;

  puts("EEPROM write:");
  f2b xx = { .fn = nr, };
  printf("nr = %.2f, %a, %08x\n", xx.fn, xx.fn, xx.ib);
  for (size_t x_ = 0; x_ < sizeof(float); ++x_) {
    eeprom_write(x_ + of0, xx.fb[x_]);
  }
  putchar('\n');

  puts("EEPROM write:");
  f2b xz = { .fn = ns, };
  printf("ns = %.2f, %a, %08x\n", xz.fn, xz.fn, xz.ib);
  for (size_t x_ = 0; x_ < sizeof(float); ++x_) {
    eeprom_write(x_ + of1, xz.fb[x_]);
  }
  putchar('\n');

  puts("EEPROM read:");
  f2b qx;
  for (size_t x_ = 0; x_ < sizeof(float); ++x_) {
    qx.fb[x_] = eeprom_read(x_ + of0);
  }

  f2b yx;
  for (size_t x_ = 0; x_ < sizeof(float); ++x_) {
    yx.fb[x_] = qx.fb[x_];
  }
  printf("nr = %.2f, %a, %08x\n", yx.fn, yx.fn, yx.ib);
  putchar('\n');

  puts("EEPROM read:");
  f2b qz;
  for (size_t x_ = 0; x_ < sizeof(float); ++x_) {
    qz.fb[x_] = eeprom_read(x_ + of1);
  }

  f2b yz;
  for (size_t x_ = 0; x_ < sizeof(float); ++x_) {
    yz.fb[x_] = qz.fb[x_];
  }
  printf("ns = %.2f, %a, %08x\n", yz.fn, yz.fn, yz.ib);
  putchar('\n');

  return 0;
}
by

C Language online compiler

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!

Read inputs from stdin

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;
    
}

About C

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.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

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.

2. Switch:

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;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

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 
}

5. Do-While:

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);

Arrays

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.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

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

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}