strcpy

Char and strcpy in C

与世无争的帅哥 提交于 2021-02-05 12:32:59
问题 I came across a part of question in which, I am getting an output, but I need a explanation why it is true and does work? char arr[4]; strcpy(arr,"This is a link"); printf("%s",arr); When I compile and execute, I get the following output. Output: This is a link 回答1: The short answer why it worked (that time) is -- you got lucky. Writing beyond the end of an array is undefined behavior . Where undefined behavior is just that, undefined , it could just a easily cause a segmentation fault as it

C++ How to populate a static array of strings with new strings in different locations?

时光毁灭记忆、已成空白 提交于 2021-02-05 12:28:18
问题 Say I got this char* MapIds[5000] = { "Northeast Asia","Hanyang","Pusan","Pyongyang","Shanghai","Beijing","Hong Kong", /*...5000 values etc../* }; I tried strcpy(MapIds[0], "gfggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg"); But it crashes How Do I keep changing them around without messing up the strings in other elements. I dont want to use std::string or vector those cause crazy slow compile times. 回答1: Because you try to copy into a

Modifying a String (char array) [closed]

老子叫甜甜 提交于 2021-01-28 03:23:00
问题 Closed. This question needs debugging details. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 11 months ago . Improve this question I am trying to modify a string in C language char signal_cat[8]; if (k == 1) { strcpy_s(signal_cat, "HPHA",6); //why cant I change char array (string) values??? } else if (k == 2) { strcpy_s(signal_cat, "Normal",6); } printf("Original signal category: %s \n", signal_cat); When

Modifying a String (char array) [closed]

我的梦境 提交于 2021-01-28 02:12:14
问题 Closed. This question needs debugging details. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 11 months ago . Improve this question I am trying to modify a string in C language char signal_cat[8]; if (k == 1) { strcpy_s(signal_cat, "HPHA",6); //why cant I change char array (string) values??? } else if (k == 2) { strcpy_s(signal_cat, "Normal",6); } printf("Original signal category: %s \n", signal_cat); When

What exactly is -fno-builtin doing here?

ⅰ亾dé卋堺 提交于 2020-06-09 04:11:15
问题 So I was reading Hacking the Art of Exploitation and in the book, they use the strcpy() function in their C code: 1 #include <stdio.h> 2 #include <string.h> 3 4 int main() { 5 char str_a[20]; 6 7 strcpy(str_a, "Hello, world!\n"); 8 printf(str_a); 9 } They then proceed to compile their source code and analyze it with gdb . He sets a breakpoint on line 6, the strcpy function, and line 8, but when setting a break on strcpy it reads the following: (gdb) break strcpy Function "strcpy" not defined.

C语言字符串

本秂侑毒 提交于 2020-03-15 18:00:54
目录 一、字符串的概念 二、占用内存的情况 三、字符串的初始化 四、字符串与指针 五、字符串的结尾标志 六、字符串的输出 七、字符串越界 八、字符串常用的库函数 1、获取字符串的长度(strlen) 2、字符串复制或赋值(strcpy) 3、字符串复制或赋值(strncpy) 4、字符串拼接(strcat) 5、字符串拼接(strncat) 6、字符串比较(strcmp、strncmp) 7、字符查找(strchr、strrchr) 8、字符串查找(strstr) 九、应用经验 1、留有余地 2、变量初始化 3、位置(地址)偏移的用法 4、不要在子函数中对字符指针用sizeof 十、课后作业 十一、版权声明 在很多教程中,字符串不过是一个以0结束的字符数组,但是,在我看来,字符串虽然不是C语言基本数据类型,但它比任何数据类型都重要,因为字符串是最常用的数据。 一、字符串的概念 我们可以把字符串储存在char类型的数组中,如果char类型的数组末尾包含一个表示字符串末尾的空字符\0,则该数组中的内容就构成了一个字符串。 因为字符串需要用\0结尾,所以在定义字符串的时候,字符数组的长度要预留多一个字节用来存放\0,\0就是数字0。这是约定。 char strname[21]; // 定义一个最多存放20个英文字符或十个中文的字符串 字符串也可以存放中文和全角的标点符号

笔记strlen() ,sizeof(),strcpy(),strncpy(),strcat()

依然范特西╮ 提交于 2020-03-13 12:47:18
strlen函数的意思是测试字符串的字符长度,不含字符串结束标志的。 int strlen( const char *str) { assert(str != NULL); int len; while((*str++) != '\0') { len++; } return len; } sizeof是运算符,它的结果是字符串在内存中的所占字节大小,它要把\0算进去的。 strcpy函数原型 ( strcpy(s1,s2); strcpy函数的意思是:把字符串s2中的内容copy到s1中,连字符串结束标志也一起copy ) char *strcpy(char *strDest, const char *strSrc)//strDest为目标,strSrc为源 { assert((strDest!=NULL) && (strSrc !=NULL)); //如果两个为空则不用复制,直接中止 char *address = strDest; //用address指向strDest开始地址 while( (*strDest++ = * strSrc++) != ‘\0’ ) //复制,直到源串结束; NULL ; //空操作 return address ; //返回strDest开始地址 } } strncpy函数 : 利用标准库函数strncpy(),可以