I use curly braces with all of my switch case statements in C/Objective-C/C++
I had not, until a few moments ago, considered whether including thebreak;statement inside the braces was good or bad practice. I suspect that it doesn't matter, but I figure it is still worth asking.
Just a give a slightly more detailed answer...
The official C99 specification says the following about the break statement:
A break statement terminates execution of the smallest enclosing switch or iteration statement.
So it really doesn't matter. As for me, I put the break inside the curly braces. Since you can also have breaks in other places inside your curly braces, it's more logical to also have the ending break inside the braces. Kind of like the return statement.
In this blog post, we will see the C program to convert Hexadecimal to Decimal. In the interview, people ask the below questions,
How will you convert hexadecimal to decimal value?
Write a C program to convert hexadecimal number system value to decimal number system?
Implement logic to convert a hexadecimal number to a decimal number system?
Get a hexadecimal number from the user and convert it to its decimal equivalent?
Examples:
Input :67
Output :103
Input :512
Output :1298
Input: 123
Output: 291
We need to know the decimal and hexadecimal numbers before writing the C program to convert hexadecimal to the decimal.
The hexadecimal number system is a base 16 number system. The hexadecimal number is represented by 16 values i.e 0 1 2 3 4 5 6 7 8 9 A B C D E F.
The decimal number system is a base 10 number system. It uses 10 symbols to represent all numbers i.e. 0123456789
Logic to convert Hexadecimal to Decimal System:
We know that in hexadecimal number uses 16 symbols {0, 1, 2, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F} to represent all numbers. Here, (A, B, C, D, E, F) represents (10, 11, 12, 13, 14, 15).
We need to run a loop from 0 to (buffer_length -1). The buffer_length is the length of the buffer which contains entered hexadecimal number.
To convert hex to decimal, we need to extract the digits of a given hexadecimal number from the buffer. At the time of extracting digits from the hexadecimal number, multiply the digit with the proper base (Power of 16) and add it to the variable “decimal”.
After ending the iteration, the variable “decimal” will store the resultant decimal number.
For Example: If the hexadecimal number is 1A. decimal = 1*(16^1) + 10*(16^0) = 26
Below diagram explains how to convert hexadecimal number ( 1AB ) to equivalent decimal value:
C Program to convert hexadecimal to decimal number system:
#include <stdio.h>
#include <math.h>
#include <string.h>
#define ARRAY_SIZE 20
int main()
{
char hex[ARRAY_SIZE];
long long decimal = 0, base = 1;
int i = 0, value, length;
/* Get hexadecimal value from user */
printf("Enter hexadecimal number: ");
fflush(stdin);
fgets(hex,ARRAY_SIZE,stdin);
length = strlen(hex);
for(i = length--; i >= 0; i--)
{
if(hex[i] >= '0' && hex[i] <= '9')
{
decimal += (hex[i] - 48) * base;
base *= 16;
}
else if(hex[i] >= 'A' && hex[i] <= 'F')
{
decimal += (hex[i] - 55) * base;
base *= 16;
}
else if(hex[i] >= 'a' && hex[i] <= 'f')
{
decimal += (hex[i] - 87) * base;
base *= 16;
}
}
printf("\nHexadecimal number = %s", hex);
printf("Decimal number = %lld\n", decimal);
return 0;
}
Enter hexadecimal number: 1A
Hexadecimal number = 1A
Decimal number = 26
First, explain that the delay function of the first atomic brother is no problem. Atomic brother's delay function is used in STM32F103, depending on the type of development board. Here are the delay functions of STM32F103 and STM32F030.
(1) Used in STM32F030:
#include "stm32f0xx.h"
#include "delay.h"
//////////////////////////////////////////////////////////////////////////////////
//This program is for learning use only and cannot be used for any other purpose without permission from the author
//Mini STM32 development board
//Use SysTick's normal counting mode to manage the delay
//Including delay_us, delay_ms
//Punctual atom @ALIENTEK
//Technical Forum: www.openedv.com
//Date of modification: 2010/5/27
//Version: V1.2
//Copyright, piracy will be investigated.
//Copyright(C) punctual atom 2009-2019
//All rights reserved
//********************************************************************************
//V1.2 modification instructions
//Fixed the error that the call in the interrupt occurs in an infinite loop
//To prevent inaccurate delay, use do while structure!
//////////////////////////////////////////////////////////////////////////////////
static u8 fac_us=0;//us delay multiplier
static u16 fac_ms=0;//ms delay multiplier
//Initialize delay function
//The clock of SYSTICK is fixed at 1/8 of the HCLK clock
//SYSCLK: system clock
void delay_init(u8 SYSCLK)
{
SysTick->CTRL&=0xfffffffb;//bit2 clear, select external clock HCLK/8
fac_us=SYSCLK/8;
fac_ms=(u16)fac_us*1000;
}
//Delay nms
//Note the range of nms
//SysTick->LOAD is a 24-bit register, so the maximum delay is:
//nms<=0xffffff*8*1000/SYSCLK
//SYSCLK unit is Hz, nms unit is ms
//For 72M, nms<=1864
void delay_ms(u16 nms)
{
u32 temp;
SysTick->LOAD=(u32)nms*fac_ms;//Time loading (SysTick->LOAD is 24bit)
SysTick->VAL =0x00; //Clear counter
SysTick->CTRL=0x01; //Start countdown
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));//Wait time to arrive
SysTick->CTRL=0x00; //Turn off the counter
SysTick->VAL =0X00; //Clear counter
}
//Delay nus
//nus is the number of us to be delayed.
void delay_us(u32 nus)
{
u32 temp;
SysTick->LOAD=nus*fac_us; //Time to load
SysTick->VAL=0x00; //Clear counter
SysTick->CTRL=0x01; //Start countdown
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));//Wait time to arrive
SysTick->CTRL=0x00; //Turn off the counter
SysTick->VAL =0X00; //Clear counter
}
