strncmp

Finding words with the same first character

由 北战南征 提交于 2020-06-29 02:41:44
问题 I've made an array and now I'm trying to compare first symbols of two strings and if it's true to print that word. But I got a problem: Incompatible types in assignmentof "int" to "char"[20]" Here is the code: for ( wordmas= 0; i < character; i++ ) { do { if (!strncmp(wordmas[i], character, 1) } puts (wordmas[i]); } Maybe you guys could help me? 回答1: There are several issues with your code: You do not need strncmp to compare the first character - all you need is a simple == or != . Using a do

C语言 strncmp

由 时间秒杀一切 提交于 2020-02-28 19:45:06
C语言 strncmp #include <string.h> int strncmp(const char *s1, const char *s2, size_t n); 功能：比较 s1 和 s2 前n个字符的大小，比较的是字符ASCII码大小。 参数： s1：字符串1首地址 s2：字符串2首地址 n：指定比较字符串的数量 返回值： 相等：0 大于： > 0 小于： < 0 案例 #define _CRT_SECURE_NO_WARNINGS #include <stdio.h> #include <string.h> #include <stdlib.h> #include <math.h> #include <time.h> int main(void) { char ch1[] = "hello world"; char ch2[] = "hallo world"; // 两个有限字符串比较 int value = strncmp(ch1, ch2); // 返回为1不相等 printf("%d\n", value); return 0; } strncmp 使用案例：使用函数 #define _CRT_SECURE_NO_WARNINGS #include <stdio.h> #include <string.h> #include <stdlib.h>

linux网络多线程编程实例

由 让人想犯罪 __ 提交于 2020-02-24 14:43:06
用的是UDP方式。 服务器能同时接受十个客户端，各个客户端可以相互点对点通讯；可以对所有连到 服务器的客户端广播；也可以和服务器通讯。服务器也可以广播。 运行时你要先看懂源代码中的命令: "/w " 广播 ； "/s n " 对某个客户端； "/sv "对服务器； 命令是引号中的部分，注意空格。 服务端代码： #include<sys/stat.h> #include<fcntl.h> #include<unistd.h> #include<sys/types.h> #include<sys/socket.h> #include <sys/wait.h> #include <netinet/in.h> #include<arpa/inet.h> #include<stdio.h> #include<string.h> #include<stdlib.h> #include <pthread.h> #define PORT 8889 #define max_size 256 ///////////////////////////////////////////////////////// int sockfd,sockfd2[10],ret,i=0,j,flag=0; struct sockaddr_in addr; struct sockaddr_in addr2[10]; int

Why does the compiler optimize away shared memory reads due to strncmp() even if volatile keyword is used?

由 好久不见. 提交于 2019-12-22 09:57:09
问题 Here is a program foo.c that writes data to shared memory. #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <stdint.h> #include <unistd.h> #include <sys/ipc.h> #include <sys/shm.h> int main() { key_t key; int shmid; char *mem; if ((key = ftok("ftok", 0)) == -1) { perror("ftok"); return 1; } if ((shmid = shmget(key, 100, 0600 | IPC_CREAT)) == -1) { perror("shmget"); return 1; } printf("key: 0x%x; shmid: %d\n", key, shmid); if ((mem = shmat(shmid, NULL, 0))

Why is string comparison so fast in python?

由 雨燕双飞 提交于 2019-12-18 11:44:16
问题 I became curious to understand the internals of how string comparison works in python when I was solving the following example algorithm problem: Given two strings, return the length of the longest common prefix Solution 1: charByChar My intuition told me that the optimal solution would be to start with one cursor at the beginning of both words and iterate forward until the prefixes no longer match. Something like def charByChar(smaller, bigger): assert len(smaller) <= len(bigger) for p in

Why is fgets() and strncmp() not working in this C code for string comparison?

由 核能气质少年 提交于 2019-12-12 20:29:03
问题 This is a very fun problem I am running into. I did a lot of searching on stack overflow and found others had some similar problems. So I wrote my code accordingly. I originally had fscan() and strcmp() , but that completely bombed on me. So other posts suggested fgets() and strncmp() and using the length to compare them. I tried to debug what I was doing by printing out the size of my two strings. I thought, maybe they have /n floating in there or something and messing it up (another post

Comparing a single string to an array of strings in C

由 ≯℡__Kan透↙ 提交于 2019-12-11 07:54:03
问题 My program is accepting user input and then taking the first word inputted and comparing it to an array of accepted commands. What would be the best way to compare the first word inputted (after it has been tokenized) to an array of strings? Example: comparing the string "pwd" to an array containging {"wait", "pwd", "cd", "exit"} Thanks in advance for your help! 回答1: I would do something like the following: int string_in(const char* string, const char** strings, size_t strings_num) { for

Why does the compiler optimize away shared memory reads due to strncmp() even if volatile keyword is used?

由 爷，独闯天下 提交于 2019-12-05 20:14:58
Here is a program foo.c that writes data to shared memory. #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <stdint.h> #include <unistd.h> #include <sys/ipc.h> #include <sys/shm.h> int main() { key_t key; int shmid; char *mem; if ((key = ftok("ftok", 0)) == -1) { perror("ftok"); return 1; } if ((shmid = shmget(key, 100, 0600 | IPC_CREAT)) == -1) { perror("shmget"); return 1; } printf("key: 0x%x; shmid: %d\n", key, shmid); if ((mem = shmat(shmid, NULL, 0)) == (void *) -1) { perror("shmat"); return 1; } sprintf(mem, "hello"); sleep(10); sprintf(mem, "exit");

内核发送uevent的API，用户空间解析uevent（转）

由 妖精的绣舞 提交于 2019-12-03 11:07:11
#include <stdio.h> #include <string.h> #include <sys/types.h> #include <unistd.h> #include <stdlib.h> #include <sys/socket.h> #include <linux/netlink.h> #define UEVENT_MSG_LEN 4096 struct luther_gliethttp { const char *action; const char *path; const char *subsystem; const char *firmware; int major; int minor; }; static int open_luther_gliethttp_socket(void); static void parse_event(const char *msg, struct luther_gliethttp *luther_gliethttp); int main(int argc, char* argv[]) { int device_fd = -1; char msg[UEVENT_MSG_LEN+2]; int n; device_fd = open_luther_gliethttp_socket(); printf("device_fd =

Why is string comparison so fast in python?

由 家住魔仙堡 提交于 2019-11-30 06:06:14
I became curious to understand the internals of how string comparison works in python when I was solving the following example algorithm problem: Given two strings, return the length of the longest common prefix Solution 1: charByChar My intuition told me that the optimal solution would be to start with one cursor at the beginning of both words and iterate forward until the prefixes no longer match. Something like def charByChar(smaller, bigger): assert len(smaller) <= len(bigger) for p in range(len(smaller)): if smaller[p] != bigger[p]: return p return len(smaller) To simplify the code, the
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