C语言 fgets 跳过空行
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fgets skip the blank line
提问by user4075830
I am writing a C program that use fgets to read in each line from a file. The problem is that if the file have a blank line, how to skip it to get the next line ? This is what I had try so far but it did not work.
我正在编写一个 C 程序，它使用 fgets 从文件中读取每一行。问题是，如果文件有一个空行，如何跳过它以获取下一行？这是我迄今为止尝试过的，但没有奏效。
char line[100];
FILE *filePtr = fopen(filename, "r");
while(fgets(line, sizeof(line), filePtr) != NULL) //read each line of the file
{
if (line != "\n")
{
//do something
}
else
{
continue;
}
}
回答by Ashish_Deshpande
You can also use the strcmp function to check for newline
您还可以使用 strcmp 函数检查换行符
//Check for dos and unix EOL format
if(strcmp(line,"\n") || strcmp(line,"\r\n"))
{
//do something
}
else
{
continue;
}
Also, answering to your comment, fgets increments the file pointer after reading the line from the file. If you are running the code on a Linux system, try doing man fgetsfor more details.
此外，回答您的评论， fgets 在从文件中读取行后增加文件指针。如果您在 Linux 系统上运行代码，请尝试执行man fgets以获取更多详细信息。
回答by timrau
Change
改变
if (line != "\n")
into
进入
if (line[0] != '\n')
回答by J.M.I. MADISON
if(strcmp(line,"\n") || strcmp(line,"\r\n")){...} is wrong.
if(strcmp(line,"\n") || strcmp(line,"\r\n")){...} 是错误的。
strcmp returns non-zero if not equal to.
如果不等于，strcmp 返回非零值。
line=="\n"
行=="\n"
line=="\r\n"
行=="\r\n"
line=="A"
行==“A”
Would all evaluate to true for this logic.
对于这个逻辑，所有评估结果都为真。
It has the right idea in mindand was helpful though.
它有正确的想法，但很有帮助。
Here is a full working program re-write:
这是一个完整的工作程序重写：
//:for: uint32_t
#include <stdint.h>
//:for: fopen, fgets, feof, fflush
#include <stdio.h>
int main(){
printf("[BEG:main]\n");fflush(stdout);
size_t num_non_empty_lines_found = 0;
FILE* file_pointer = NULL;
const char* file_name = "RFYT.TXT";
file_pointer = fopen( file_name, "r" );
//: Init to null character because fgets
//: will not change string if file is empty.
//: Leading to reporting that an empty file
//: contains exactly 1 non-blank line.
//:
//: Macro contains todays date, as a paranoid
//: measure to ensure no collisions with
//: other people's code.
#define JOHN_MARKS_MAX_LINE_2019_03_03 256
char single_line[
JOHN_MARKS_MAX_LINE_2019_03_03
] = "##代码##";
int max_line = JOHN_MARKS_MAX_LINE_2019_03_03;
#undef JOHN_MARKS_MAX_LINE_2019_03_03
//: This could happen if you accidentially
//: spelled the filename wrong:
if(NULL==file_pointer){
printf("[ERROR:CheckFileNameSpelling]\n");
return( 1 );
};;
//# DONT DO THIS! If you spelled the file #//
//# name wrong, this condition will lead #//
//# to an infinite loop. #//
//- while( !feof(file_pointer )){ ... } -//
while(fgets(
/**/single_line
, max_line
, file_pointer
)){
//: Check for empty lines:
if( strcmp(single_line,"\n" ) != 0 &&
strcmp(single_line,"\r\n") != 0 &&
strcmp(single_line,"##代码##" ) != 0 &&
1){
printf("[LINE_HAS_CONTENT]\n");
num_non_empty_lines_found++;
}else{
printf("[LINE_IS_EMPTY]\n");
continue;
};;
//: Do stuff with non empty line:
printf( "[Content]:%s\n", single_line );
};;
if(num_non_empty_lines_found<1){
printf("[WARNING:FileWasEmpty]\n");
printf("[EmptyFileName]:%s\n", file_name);
fflush(stdout);
};;
printf("[END:main]\n");fflush(stdout);
return( 0 );
};;
