strcmp

strcmp的用法

由 痞子三分冷 提交于 2019-12-27 17:47:21
字符串比较函数，一般形式为strcmp(字符串1，字符串2)。 比较规则： 对两个字符串自左至右逐个字符相比（按ASCII码值大小比较），直到出现不同的字符或遇到‘\0’为止。如果全部字符相同，则认为相等；若出现不相同的字符，则以第一个不相同的字符的比较结果为准。 如果两个字符串都由英文字母组成，则有一个简单的规律：在英文字典中位置在后面的为“大”，还要特别注意：小写字母比大写字母“大”。 返回值： （1）字符串1=字符串2，返回0 （2）字符串1>字符串2，返回一个正整数 （3）字符串1<字符串2，返回一个负整数。 来源： CSDN 作者： Almost Blue 链接： https://blog.csdn.net/weixin_45516802/article/details/103733031

c风格字符串函数

由 一曲冷凌霜 提交于 2019-12-26 03:08:23
十一、C 风格字符串 1）字符串操作 strcpy(p, p1) 复制字符串 strncpy(p, p1, n) 复制指定长度字符串 strcat(p, p1) 附加字符串 strncat(p, p1, n) 附加指定长度字符串 strlen(p) 取字符串长度 strcmp(p, p1) 比较字符串 strncmp(p, p1, n) 比较指定长度字符串 strchr(p, c) 在字符串中查找指定字符 strrchr(p, c) 在字符串中反向查找 strstr(p, p1) 查找字符串 strpbrk(p, p1) 以目标字符串的所有字符作为集合，在当前字符串查找该集合的任一元素 strspn(p, p1) 以目标字符串的所有字符作为集合，在当前字符串查找不属于该集合的任一元素的偏移 strcspn(p, p1) 以目标字符串的所有字符作为集合，在当前字符串查找属于该集合的任一元素的偏移 * 具有指定长度的字符串处理函数在已处理的字符串之后填补零结尾符 2）字符串到数值类型的转换 strtod(p, ppend) 从字符串 p 中转换 double 类型数值，并将后续的字符串指针存储到 ppend 指向的 char* 类型存储。 strtol(p, ppend, base) 从字符串 p 中转换 long 类型整型数值，base 显式设置转换的整型进制，设置为 0

C中 strcmp() 与 strcpy()

由 允我心安 提交于 2019-12-25 22:48:31
头文件： #include <string.h> 一、strcmp() 函数 函数原型： int strcmp(const char *str1, const char *str2) 参数 str1 -- 要进行比较的第一个字符串。 str2 -- 要进行比较的第二个字符串。 返回值 该函数返回值如下： 如果返回值 < 0，则表示 str1 小于 str2。 如果返回值 > 0，则表示 str2 小于 str1。 如果返回值 = 0，则表示 str1 等于 str2。 即：两个字符串自左向右逐个字符相比（按ASCII值大小相比较），直到出现不同的字符或遇'\0'为止。如： 1."A"<"B" 2."A"<"AB" 3."Apple"<"Banana" 4."A"<"a" 5."compare"<"computer" 二、strcpy() 函数 函数原型： char *strcpy(char* dest, const char *src); 功能：把从src地址开始且含有NULL结束符的字符串复制到以dest开始的地址空间； 说明：src和dest所指内存区域不可以重叠且dest必须有足够的空间来容纳src的字符串。 返回指向dest的指针。 //C语言标准库函数strcpy的一种典型的工业级的最简实现。 //返回值：目标串的地址。 //对于出现异常的情况ANSI-C99标准并未定义

#c strcmp() isn't working as it should

由 六眼飞鱼酱① 提交于 2019-12-25 09:48:37
问题 I want to compare between two char* so i do it with strcmp, look, in debugging mode, both char* in strcmp gets the same value and still it wont return 0, and it jumps over the if() condition instead of entering it: here pic from the debugger: http://img405.imageshack.us/img405/5218/111fi.jpg Company FindCompany(CompanyL pcompanyList, int companyIdentityDigit) { Company companyFound; char *psearchWord; psearchWord = (char*)malloc(10*sizeof(char)); switch(companyIdentityDigit) { case 0: strcpy

Comparing strings in C - strcmp

由 孤者浪人 提交于 2019-12-25 01:37:00
问题 I'm having trouble comparing strings in C (with which I am fairly new to). I have socket on this server application waiting to accept data from a client. In this particular portion of my program I want to be able to execute a MySQL query based on the data received from the client. I want to be able to know when the received data has the value of "newuser" to initiate a simple registration procedure. Strcmp is returning a positive 1 value where I believe I should be getting a 0 because the

C: Palindrome: Different strlen-values

由 核能气质少年 提交于 2019-12-24 14:07:33
问题 I'm making a function which reverses a string and checks if the string is a palindrome or not. When I test the function with a obvious palindrome like "abba", the function says it's not a palindrome. Also the forward string and the reversed string also differ in string length! #include <stdio.h> #include <string.h> char forward [] = "abba"; //The string to be reversed int size = (sizeof(forward)/sizeof(forward[0]) - 1); int j = 0; char reverse [10]; void reverser(char forward []) { printf("%s

Compare between a char in a string to a given char

由 佐手、 提交于 2019-12-22 04:17:09
问题 I have the following: int findPar(char* str) { int counter=0; while (*str) { if(str[0] == "(") <---- Warning { counter++; } else if (str[0]== ")") <---- Warning { counter--; } if (counter<0) { return 0; } str++; } if (counter!=0) { return 0; } return 1; } The warning i get is comparison between an int and a char. I tried to do the comparison (first char in the string vs. given char) also with strcmp like this: if (strcmp(str, ")")==0) { stuff } but it never goes in to 'stuff' even when the

Swift why strcmp of backspace returns -92?

由 冷暖自知 提交于 2019-12-21 19:21:08
问题 I was tried to detecting backspace inside of UITextfieldDelegate. And found this answer. https://stackoverflow.com/a/49294870/911528 And It working correctly. But I don't know what's going on inside of this function. let char = string.cString(using: String.Encoding.utf8)! let isBackSpace = strcmp(char, "\\b") if isBackSpace == -92 { print("Backspace was pressed") return false } I don't know why the result of cString of backspace is 0. I can debug on XCode. Please check the screenshot. I don't

Swift why strcmp of backspace returns -92?

由 假装没事ソ 提交于 2019-12-21 19:20:19
问题 I was tried to detecting backspace inside of UITextfieldDelegate. And found this answer. https://stackoverflow.com/a/49294870/911528 And It working correctly. But I don't know what's going on inside of this function. let char = string.cString(using: String.Encoding.utf8)! let isBackSpace = strcmp(char, "\\b") if isBackSpace == -92 { print("Backspace was pressed") return false } I don't know why the result of cString of backspace is 0. I can debug on XCode. Please check the screenshot. I don't

Optimized strcmp implementation

由 谁说我不能喝 提交于 2019-12-21 03:47:13
问题 This function was found here. It's an implementation of strcmp : int strcmp(const char* s1, const char* s2) { while (*s1 && (*s1 == *s2)) s1++, s2++; return *(const unsigned char*)s1 - *(const unsigned char*)s2; } I understand all but the last line, in short what is going on in the last line? 回答1: return *(const unsigned char*)s1-*(const unsigned char*)s2; OP: in short what is going on in the last line? A: The first potential string difference is compared. Both chars are referenced as
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