fwrite

Writing a stream of 9 bit values as bytes to a file in C

由 无人久伴 提交于 2020-01-30 09:05:20
问题 I have an array with integer values from 0-511 (9 bits max). I am trying to write this to a file with fwrite . For Example, with the array: [257, 258, 259] Which is 100000001, 100000010, 100000011 I am trying to write 100000001100000010100000011 + extra padding of 0s to the file But since fwrite limits writes to 1 byte at a time, I am not sure how to go about doing this. I am new to bitwise operations and am not how to separate out the individual bytes. 回答1: You need a bit buffer. Since you

Writing char pointer as struct member to file issue

由 断了今生、忘了曾经 提交于 2020-01-30 08:50:05
问题 I have a struct member as a char * and assign it to a string literal "John" on the struct initialisation as shown below. The string prints fine with printf. However, if I write this string to a file using fwrite, in the file I read back garbage. If I use a char array instead of a char * (commented out in the struct as shown), and write it to the file, I can read back the string in the file as expected. I can't understand this. Shouldn't fwrite in both cases take the pointer and write the

Can't write int to file using fwrite

由 我只是一个虾纸丫 提交于 2020-01-30 07:02:06
问题 I'm trying to format my keylog output so it shows time: t = time(0); now = localtime(&t); if(now->tm_min != prevM && now->tm_hour != prevH) { prevM = now->tm_min; prevH = now->tm_hour; fwrite("[", 1, sizeof(WCHAR), keylog); fwrite(&prevH, 1, sizeof(int), keylog); fwrite("]", 1, sizeof(WCHAR), keylog); fwrite(" ", 1, sizeof(WCHAR), keylog); fflush(keylog); } but instead of readable number I get "[ DLE NUL ] " written in my file, where DLENUL is question mark. How do I make it to write a

PHP文件操作

由 夙愿已清 提交于 2020-01-23 05:27:15
PHP文件操作 计应134 凌豪 1．打开文件 在PHP中使用fopen()函数打开文件，fopen()函数的语法如下: resource fopen ( string filename, string mode [, bool use_include_path]); filename是要打开的包含路径的文件名，可以是相对路径，也可以是绝对路径。如果没有任何前缀则表示打开的是本地文件 mode是打开文件的方式，use_include_path是可选的，该参数在配置文件php.ini中指定一个路径，如F:\AppServ\ www\mess.php，如果希望服务器在这个路径下打开所指定的文件，可以设置为1或 true。 2．关闭文件 对文件的操作结束后应该关闭这个文件，否则可能引起错误。在PHP中使用fclose()函数关闭文件，该函数的语法如下： bool fclose ( resource handle ) ; 该函数将参数handle指向的文件关闭，如果成功，返回true，否则返回false 3.读写文件 •1．从文件中读取数据 1）读取整个文件：readfile()、file()和file_get_contents() （ 1）readfile()函数 readfile()函数用于读入一个文件并将其写入到输出缓冲，如果出现错误则 返回false。函数语法 如下： int

check return value fread and fwrite

由 元气小坏坏 提交于 2020-01-23 02:42:48
问题 #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]){ if(argc != 3){ printf("Usage: ./copy filename newfile\n"); exit(1); } int bytes; long file_size, file_copied_size; FILE *file_to_copy, *new_file; if((file_to_copy = fopen(argv[1], "rb")) == NULL){ printf("File cannot be opened - read\n"); exit(1); } if((new_file = fopen(argv[2], "wb")) == NULL){ printf("File cannot be opened - write\n"); exit(1); } fseek(file_to_copy, 0, SEEK_END); file_size = ftell(file_to_copy); rewind

文件操作函数（2）

由 不打扰是莪最后的温柔 提交于 2020-01-18 08:02:00
一、块读写 块读写主要涉及到两个函数fread和fwrite，这两个函数的原型是： unsigned int fread(void *buffer,unsigned int size,unsigned int n,FILE *fp); 从文件读取一组数据存放在首地址为buffer的内存空间中，size为一个数据块的大小，n为要读取的数据块的个数，若读取成功，则返回读取的数据的数据块的个数，否则返回0. unsigned int fwrite(const void *buffer,unsigned int size,unsigned int n,FILE *fp); 向文件中写入数据，写入成功返回写入数据块的个数，否则返回0. 块读写一般用于结构体。 注意: 1)块读写常用于结构体。 2)fread和fwrite一般成对出现，如果对文件进行写操作用的是fwrite，则用fread读取，否则可能会得到意想不到的结果。 二、格式化读写 格式化读写主要涉及到两个函数：fscanf和fprintf，两个函数的原型是 int fscanf(FILE *fp,const char *format[,argument]....); 用于从文件格式化读取数据，若读取成功，则返回读取的数据个数，否则返回-1 int fprintf(FILE *fp,const char *format[

Pass dynamic text input to PHP in order to write to text file

由 青春壹個敷衍的年華 提交于 2020-01-15 09:13:53
问题 building my very first website but can't figure out this last bit. My RSVP form has the following user inputs: 1) number of guests in a drop down select menu 2) Guest names 3) text area. After user selects the number, Guest name text boxes dynamically appear for name input. Once all is done, user clicks RSVP and PHP code writes it to text file. Problem: Guest number and text area writes fine but dynamic Guest name boxes don't get passed to PHP. How should I solve this? Been trying everything.

Pass dynamic text input to PHP in order to write to text file

由 坚强是说给别人听的谎言 提交于 2020-01-15 09:13:35
问题 building my very first website but can't figure out this last bit. My RSVP form has the following user inputs: 1) number of guests in a drop down select menu 2) Guest names 3) text area. After user selects the number, Guest name text boxes dynamically appear for name input. Once all is done, user clicks RSVP and PHP code writes it to text file. Problem: Guest number and text area writes fine but dynamic Guest name boxes don't get passed to PHP. How should I solve this? Been trying everything.

Pass dynamic text input to PHP in order to write to text file

由 假装没事ソ 提交于 2020-01-15 09:13:09
问题 building my very first website but can't figure out this last bit. My RSVP form has the following user inputs: 1) number of guests in a drop down select menu 2) Guest names 3) text area. After user selects the number, Guest name text boxes dynamically appear for name input. Once all is done, user clicks RSVP and PHP code writes it to text file. Problem: Guest number and text area writes fine but dynamic Guest name boxes don't get passed to PHP. How should I solve this? Been trying everything.

在一张图片中隐藏另一张图片

由 我的梦境 提交于 2020-01-14 11:42:48
首先是在灰度图中隐藏灰度图 因为是交作业嘛，为了简单就依次在每个字节中隐藏信息，如果有什么不想让人看见的东西要隐藏，可以自己有选择性的隐藏 这里先得到两张灰度图 将第二幅图片当作秘密图片插入一图，这里先将第二幅图置乱 这里采用的是菱形置乱的方法，即在菱形中从第一行开始从左向右依次写入1到n,替换时从第一列从上到下依次读取序号，即第一列序号对应的像素作为第一个像素 代码如下，这里我用的算法比较笨就将就吧，恢复置乱时只需要更改其中一条代码，在代码中已说明 再说明一下，我是将菱形补全为正方形，用0填充，方法虽笨但是能用 /* 对图片进行置乱处理 2015年6月2日20:02:18 blog：http://www.cnblogs.com/wd1001/ */ #include<stdio.h> #include<malloc.h> #include<stdlib.h> /* 位图头结构 */ #pragma pack(1) typedef struct tagBITMAPFILEHEADER { unsigned char bfType[2];//文件格式 unsigned long bfSize;//文件大小 unsigned short bfReserved1;//保留 unsigned short bfReserved2; unsigned long bfOffBits; /
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