fgets | 易学教程

PHP - Returning the last line in a file?

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I'm guessing it's fgets, but I can't find the specific syntax. I'm trying to read out (in a string I'm thinking is easier) the last line added to a log file. The simplest naive solution is simply: $file = "/path/to/file"; $data = file($file); $line = $data[count($data)-1]; Though, this WILL load the whole file into memory. Possibly a problem (or not). A better solution is this: $file = escapeshellarg($file); // for the security concious (should be everyone!) $line = `tail -n 1 $file`; Tomalak This looks like it is what you are looking for: tekkie.flashbit.net: Tail functionality in PHP It

carriage return by fgets

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问题 I am running the following code: #include<stdio.h> #include<string.h> #include<io.h> int main(){ FILE *fp; if((fp=fopen("test.txt","r"))==NULL){ printf("File can't be read\n"); exit(1); } char str[50]; fgets(str,50,fp); printf("%s",str); return 0; } text.txt contains: I am a boy\r\n Since I am on Windows, it takes \r\n as a new line character and so if I read this from a file it should store "I am a boy\n\0" in str , but I get "I am a boy\r\n" . I am using mingw compiler. 回答1: Since I am on

Reaching EOF with fgets

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问题 I'm writing a function that perform some authentications actions. I have a file with all the user_id:password:flag couples structured like this: Users.txt user_123:a1b2:0 user_124:a2b1:1 user_125:a2b2:2 This is the code: int main(){ /*...*/ /*user_id, password retrieving*/ USRPSW* p = malloc(sizeof(USRPSW)); if(p == NULL){ fprintf(stderr, "Dynamic alloc error\n"); exit(EXIT_FAILURE); } memset((void*)p, 0, sizeof(USRPSW)); if(usr_psw_read(acc_sock_ds, p->user_id, USR_SIZE) <= 0){ printf(

C语言fgets()与fputs()详解

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文章目录 fgets()与fputs() 1⃣️fgets()优缺点： 2⃣️fgets()返回值： 3⃣️fgets()操作实例： 3⃣️fgets()操作进阶： fgets()与fputs() fgets()函数的第二个参数指明了读入字符的最大数量。如果该参数为n，那么fgets函数将读入n-1个字符。如果fgets()函数读到一个换行符，会把它储存在字符串中。这点与gets不同，gets会丢弃换行符。fgets()函数的第三个参数指明要读入的文件。如果读入从键盘输入的数据，则以stdin作为参数。 fputs()函数的第二个参数指明他要写入的文件。如果要在计算机显示器上打印，则使用stdout作为参数。与puts()函数不同，fputs()函数不会在待输出字符串末尾添加一个换行符。例： # include <stdio.h> # define LEN 14 int main ( void ) { char words [ LEN ] ; puts ( "Enter a String" ) ; fgets ( words , LEN , stdin ) ; puts ( words ) ; //puts()函数会添加换行符\n fputs ( words , stdout ) ; return 0 ; } 输入apple后， apple\n\0 被存储在数组中。

How do I read white space using scanf in c?

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问题 Problem: I need to be able identify when two whitespaces occur consecutively. I have read the following questions: how to read a string from a \n delimited file how to read scanf with spaces And I am aware of scanf problems: http://c-faq.com/stdio/scanfprobs.html Input will be in the following format: 1 5 3 2 4 6 2 1 9 0 Two white spaces indicates that the next set of data needs to be handle and compared to itself. The length of the line is unknown and the number or integers in each group is

C scanf() and fgets() problem

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问题 I'm trying to read user input and store it as a string including the whitespace. I did a search for a solution and was pointed to fgets() or scanf(%[^\n], str). But both these solutions give me an error. This is what I have: //MAX_CHARACTERS is set to 30 scanf("%d", &input); if (input == 1){ int pr; char na[MAX_CHARACTERS+1]; printf("\nEnter the name: "); scanf("%[^\t\n]", &na); while (strlen(na)>MAX_CHARACTERS){ printf("\nName is too long, enter new name: "); scanf("%[^\t\n]", &na); }// end

Return value of fgets()

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问题 I have just recently started working with I/O in C . Here is my question - I have a file, from which I read my input. Then I use fgets() to get strings in a buffer which I utilise in some way. Now, what happens if the input is too short for the buffer i.e. if the first read by fgets() reaches EOF . Should fgets() return NULL (as I have read in fgets() documentation)? It seems that it doesn't and I get my input properly. Besides even my feof(input) does not say that we have reached EOF . Here

How to fgets() a specific line from a file in C?

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问题 So, I'm trying to find a way to fgets() a specific line in a text file in C, to copy the contents of the line into a more permanent buffer: Essentially, I was wondering if there was a way to do that without something similar to the following code: FILE *fp; fp = fopen(filename, "r"); char line[256]; char * buffer; int targetline = 10; while( targetline > 0) { fgets(line, 256, fp) } buffer =(char*)malloc(sizeof(char) * strlen(line)); strcpy(buffer, line); So basically I don't want to iterate

fgets()函数

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char * fgets(char * s,int size,FILE * stream); s，数据存储位置；size，读取字符串的最大数量；stream，指向FILE结构的指针。 fgets()用来从参数stream所指的文件内读入字符并存到参数s所指的内存空间，直到出现换行字符、读到文件尾或是已读了size-1个字符为止，最后会加上NULL作为字符串结束。换行符号'\n'会添加到数据最后的位置即： s[strlen(s) - 1] == '\n' int fputs(const char *s, FILE *stream); int puts(const char *s); 返回值：成功返回一个非负整数，出错返回EOF 缓冲区s中保存的是以'\0'结尾的字符串，fputs将该字符串写入文件stream，但并不写入结尾的'\0'。与fgets不同的是，fputs并不关心的字符串中的'\n'字符，字符串中可以有'\n'也可以没有'\n'。puts将字符串s写到标准输出（不包括结尾的'\0'），然后自动写一个' \n'到标准输出。他们都适合操作二进制文件转载于:https://www.cnblogs.com/liwentao1091/archive/2013/05/17/3083519.html 来源： https://blog.csdn.net/weixin

how to prevent fgets blocks when file stream has no new data

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问题 I have a popen() function which executes "tail -f sometextfile". Aslong as there is data in the filestream obviously i can get the data through fgets(). Now, if no new data comes from tail, fgets() hangs. I tried ferror() and feof() to no avail. How can i make sure fgets() doesn't try to read data when nothing new is in the file stream? One of the suggestion was select(). Since this is for Windows Platform select doesn't seem to work as anonymous pipes do not seem to work for it (see this