LabWindows/CVI
Read datas of .txt file according to the list using CVI
Hi xiepei,
paste the following lines in the interactive execution window and check that data scanning is performed correctly.
Basically, you need to open the file in ASCII mode (OpenFile) and read line-by-line (ReadLine), scanning each line as in the example and accumulating results in double arrays.
Data can then be plotted on a XY graph (better than a stripchart) provided that the X axis is formatted in absolute time: it will automatically display time figures 
#include <formatio.h> #include <ansi_c.h> static double wj, mv, ma, et; static char line[512]; static struct tm ti; // One sample line of yours
strcpy (line, "04-12-2011 14:30:58 WJ 220, MV 27.347,MA 0.114");
// Scan the line separating extracting fields
Scan (line, "%d[x]%d[x]%d[x]%d[x]%d[x]%d[x]%s[dt#]%f[x]%s[dt#]%f[x]%s[dt#]%f", &ti.tm_mday, &ti.tm_mon, &ti.tm_year, &ti.tm_hour, &ti.tm_min, &ti.tm_sec, &wj, &mv, &ma);
// Adjust fields for tm struct correct format
ti.tm_mon--; ti.tm_year -= 1900;
// Calculate timestamp
et = mktime (&ti);
My example makes intensive use of functions from the Formatting and Scanning Library: I suggest you to carefully study Scan () function help and examples, as it is a powerful instrument that has saved me several headaches while parsing data files 
Finally, I second wolfgang warning: you should better post additional informations to your original post to avoid duplicating threads.
Xiepei,
I am now ot of office and have no much time to respond, but I will give you some ideas for you to elaborate on.
Let's start examining your code:
if(FileSelectPopup ("", "*.txt", "*.txt", "Openfile", VAL_OK_BUTTON, 0, 0, 1, 0, path)){
GetFileInfo(path,&filesize);
n=sizeof(double);
frdata=(double*)malloc(filesize);
FileToArray ("外部交流电压.txt", frdata, VAL_DOUBLE, filesize/(2*n), 1, VAL_GROUPS_TOGETHER, VAL_GROUPS_AS_ROWS, VAL_ASCII);PlotY (psmppanelHandle, PSMP_PANEL_GRAPH_WJ, frdata, filesize/(2*n), VAL_DOUBLE, VAL_THIN_LINE, VAL_EMPTY_SQUARE, VAL_SOLID, 1, VAL_RED);
}
First of all, you are getting the full file pathname from FileSelectPopup but you are not using it in OpenFile!
Second, your way to calculate the array size is far from optimum: since you are reading an ASCII file you have no warranty about the lenght of your data: sizeof (double) returns 8, but depending on the precision a string represtnatation of a double number can take more or less than this (e.g "3.14" vs. "12345.2094937101841" ). Your way of calculating array size could work if used on binary files (even if it would need some trim).
Now let's go to your questions.
Q1. File garbled. You may need to add a "\n" to fprintf to separate data in rows.
Q2. See above. Additionally, with some little trick you can automate the file opening, for example if your files are named "filename.wj", "filename.wv", "filename.wa"
Q3. You can always plot a subset of values: supposing you have an array of 10000 elements, to plot only 1000 elements starting from item 2000 you can do this:
PlotY (..., ..., array + 2000, 1000, ..., ..., ..., ..., ..., ...);
