c how to extract each row of data, and how to read data row by row in c

#include

#include

using namespace std;

int main()

ifstream in("");Define an input stream in and bind it to get data from.

int x;Define a temporary variable for receiving the data read from.

for (;in >>x;The data in the input stream is fed to x via the " operator.

cout If the data in the cout is: 1 23 44 25 62 32 then output: 1 23 44 25 62 32 45 36 37 38 29

ifstream fin( ,std::ifstream::in ||std::ifstream::binary );

string strline = '"

while( getline( fin, strline) is probably like this, as for the specific type, turn it around when you use it.

This can be done using the C++ library function GetLine.

GetLine generates a string containing a string of characters read from the input stream until the following happens to cause this string to end.

1) Read the end of the file;

2) encounters the terminator specified by the function;

3) Input to the maximum.

There are two types of overloads for getline:

Parameter description: buffer: The read data will be stored in the buffer.

num: A maximum of num characters can be read. That is, the maximum amount mentioned earlier.

delim: Terminator, which will end the input when the specified terminator is encountered. In the first type of overload, the ending character is, that is, the end of the line break is encountered.

So to implement the whole line read, you can use the first overload. An example is as follows:

#include

using namespace std;

int main()

char buf[1024];Stored BUFF.

while(getline(buf,sizeof(buf))).

cout <<"read line:" <

Suppose the file is in , with no blank lines.

Use the read 1 row, and then find the beginning of the last number in each row, and read it with sscanf.

#include

main()}

for (i=0;ireturn 0;

Another way is:

Because your data has regularity, you can skip 3 and read 1. %s is a string jump.

Read a line into a string first.

string curline = getline(cin) and then parse stringstream ss from a string stream with string stream;

double cur;

ss >cur)

You can use the getline function to read the data line by line.

Resources.

Unfortunately, it is impossible for a computer to read the nth line of a txt file with a time complexity of o(1).

To read row n-1 must be found => row n-2 must be found ....Row 1 must be found. Therefore, reading the string of the 5000th line can only be found line by line, just like a human reading a book, to see the 5000th paragraph (the 5000th line of txt is actually printed out as the 5000th paragraph) must be counted paragraph by paragraph, otherwise it can only be estimated, and it is not accurate.

If you want to locate the nth "row" or the nth record with o(1) time complexity, you must use "index storage", "hash storage", etc., such as database files. For specific details, you can learn "Data Structure", "Database Principles", etc.

#include

Read the filename file (path), line whichline+1 text.

char * readspeacialline(char *filename, int whichline)

while (!feof(fp))

fgets(strline, 1024, fp);Read one row and navigate to the next row.

currentline++;

fclose(fp);Close the file.

return null;

int main()

#include

#define maxc 1024

int readspeacialline(int i)while (1)

elsewhile (1) }

end:fclose(fp);Close the file.

return ret;

Using the fgets function, fgets is read one row at a time.

Use memset to clear the strline to prevent the content in the last strline from not being cleared.

Sit back and wait, there shouldn't be a better way to locate how many lines there are, unless the file is loaded in the first place.