char

How to convert a single char into an int

由 时光怂恿深爱的人放手 提交于 2020-04-23 04:21:10
问题 I have a string of digits, e.g. "123456789", and I need to extract each one of them to use them in a calculation. I can of course access each char by index, but how do I convert it into an int? I've looked into atoi(), but it takes a string as argument. Hence I must convert each char into a string and then call atoi on it. Is there a better way? 回答1: You can utilize the fact that the character encodings for digits are all in order from 48 (for '0') to 57 (for '9'). This holds true for ASCII,

getting the first n elements of a specified char array arduino

由 本秂侑毒 提交于 2020-04-17 21:13:06
问题 My aim is reading some string from serial for example 234124!3455addg#5867 if the program sees ! it should start to add it to a char array and if it sees # it should return the first 4 elements of that char array for my example the return should be 3455. How can I solve it? I made this using String class but I need to implement it to char array. I am quite new on arduino so please be clear thank you. Here is my code: const char *s = "123123123!0037selam#aaaaSDSDa"; const char *CHAR1 = "!";

getting the first n elements of a specified char array arduino

由 点点圈 提交于 2020-04-17 21:11:43
问题 My aim is reading some string from serial for example 234124!3455addg#5867 if the program sees ! it should start to add it to a char array and if it sees # it should return the first 4 elements of that char array for my example the return should be 3455. How can I solve it? I made this using String class but I need to implement it to char array. I am quite new on arduino so please be clear thank you. Here is my code: const char *s = "123123123!0037selam#aaaaSDSDa"; const char *CHAR1 = "!";

C# - How to convert string to char?

由 余生颓废 提交于 2020-04-12 08:18:09
问题 I am a beginner in C# and I would like to know how to convert strings to chars, specifically string[] to char[] . I tried ToCharArray() , but I then I got an error saying that it doesn't exist. Convert.ToChar(<char here>) gives me a error saying cannot convert from "char" to "System.Array" 回答1: Use: string str = "Hello"; char[] characters = str.ToCharArray(); If you have a single character string, You can also try string str = "A"; char character = char.Parse(str); //OR string str = "A"; char

C# - How to convert string to char?

由 帅比萌擦擦* 提交于 2020-04-12 08:15:28
问题 I am a beginner in C# and I would like to know how to convert strings to chars, specifically string[] to char[] . I tried ToCharArray() , but I then I got an error saying that it doesn't exist. Convert.ToChar(<char here>) gives me a error saying cannot convert from "char" to "System.Array" 回答1: Use: string str = "Hello"; char[] characters = str.ToCharArray(); If you have a single character string, You can also try string str = "A"; char character = char.Parse(str); //OR string str = "A"; char

C语言进阶之路（一）----C语言的内存四区模型

由 这一生的挚爱 提交于 2020-04-07 21:51:32
1.内存四区模型： 操作系统给C/C++编写的程序分配内存，通常将分配的内存划分为以下四个区域： 1.1栈区（stack）：栈stack是一种先进后出的内存结构，所有的局部变量，函数的形参都是由编译器自动放出栈中，当一个自动变量超出其作用域时，自动从栈中弹出，用完由操作系统自动释放 1.2堆区（heap）：堆区需要程序员手动分配,手动释放，在C语言中可使用malloc进行分配。 1.3数据区： 静态区：全局变量以及程序中的静态变量。 常量区（static）：字符串、常量。C编译器对于相同的字符串会自动进行优化分配为统一的地址。 1.4代码区： 存放程序的二进制代码，程序被操作系统加载到内存的时候，所有的可执行代码都加载到代码区，也叫代码段，这块内存是不可以在运行期间修改的。 例子： //main.cpp int a = 0; //全局初始化区 char *p1; //全局未初始化区 main() { int b; //栈 char s[] = "abc"; //栈 ，编译时将"abc"存储到常量区，运行时将常量区的值拷贝靠栈区。 char *p2; //栈 char *p3 = "123456"; //123456\\0在常量区，p3在栈上。 static int c =0;//全局（静态）初始化区 p1 = (char *)malloc(10); p2 = (char *

车站售票系统

由 妖精的绣舞 提交于 2020-04-07 19:38:36
#include <windows.h> #include <conio.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #define EmFile "C:\\zm.txt" //密码帐号文件名 #define N 3 #define TEMP 2 #define TRUE 1 #define FALSE 0 int shoudsave=0 ; int count1=0,count2=0,mark=0,mark1=0 ; struct train { char num[10];//列车号 char city[10];//目的城市 char takeoffTime[10];//发车时间 char receiveTime[10];//到达时间 int price;//票价 int bookNum ;//票数 int leftbookNum; }; //订票人的信息 struct man { char num[10];//ID char name[10];//姓名 int bookNum ;//需求的票数 char password[7];//密码 int tag; }; //定义火车信息链表的结点结构 typedef struct node { struct train data ; struct node

pta A1065 A+B and C (64bit) (20分) 大数求和比大小

由 我的未来我决定 提交于 2020-04-07 17:23:57
https://pintia.cn/problem-sets/994805342720868352/problems/994805406352654336 Given three integers A, B and C in [−2​^63​​,2^​63​​], you are supposed to tell whether A+B>C我的测试数据如下： 8 -9223372036854775807 -9223372036854775808 3 9223372036854775807 9223372036854775808 -100000000000000 -9223372036854775807 -9223372036854775808 -3 9223372036854775807 9223372036854775808 3 -9223372036854775807 9223372036854775808 -3 -9223372036854775807 9223372036854775808 3 9223372036854775807 -9223372036854775808 -3 9223372036854775807 -9223372036854775808 3 #include<stdio.h> #include<string.h> //1065 A+B and C

攻防世界-reverse

由 那年仲夏 提交于 2020-04-07 15:46:30
前言 终于完成例如reverse新手区试题，总结一下 目录 前言 第一题 Hello, CTF 第二题 open-source 第三题simple-unpack 第四题logmein13 第一题 Hello, CTF 下载文件直接IDA打开。main函数如下 int __cdecl main(int argc, const char **argv, const char **envp) { signed int v3; // ebx char v4; // al int result; // eax int v6; // [esp+0h] [ebp-70h] int v7; // [esp+0h] [ebp-70h] char v8; // [esp+12h] [ebp-5Eh] char v9[20]; // [esp+14h] [ebp-5Ch] char v10; // [esp+28h] [ebp-48h] __int16 v11; // [esp+48h] [ebp-28h] char v12; // [esp+4Ah] [ebp-26h] char v13; // [esp+4Ch] [ebp-24h] strcpy(&v13, "437261636b4d654a757374466f7246756e");//关键代码 while ( 1 ) { memset(&v10,

80C51存储器与C51内存优化

由 一个人想着一个人 提交于 2020-04-07 12:13:32
80C51在物理结构上有四个存储空间：片内程序存储器、片外程序存储器、片内数据存储器和片外数据存储器。但在逻辑上，即从用户使用的角度上，80C51有三个存储空间：片内外统一编址的64KB的程序存储器地址空间（用16位地址）、256B的片内数据存储器的地址空间（用8位地址，其中128B的专用寄存器地址空间仅有21个字节有实际意义）以及64KB片外存储器地址空间。 1、程序存储器 程序存储器用于存放编好的程序和表格常数。80C51片内有4KB ROM，片外16位地址线最多可扩展64KB ROM，两者是统一编址的。如果EA端保持高电平，80C51的程序计数器PC在0000H——0FFFH范围内（即前4KB地址）是执行片内ROM的程序。当寻址范围在1000H——FFFFH时，则从片外存储器取指令。当EA端保持低电平时，80C51的所有取指令操作均在片外程序存储器中进行，这时片外存储器可以从0000H开始编址。 程序存储器中，以下6个单元具有特殊功能。 0000H：80C51复位后，PC=0000H，即程序从0000H开始执行指令。 0003H：外部中断0入口。 000BH：定时器0溢出中断入口。 0013H：外部中断1入口。 001BH：定时器1溢出中断入口。 0023H：串行口中断入口。 2、数据存储器 数据存储器用于存放中间运算结果、数据暂存和缓冲、标志位等。80C51片内有256B
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