如何使用 C 從 .txt 文件中讀取最后 3 個變量值
[英]How to read last 3 variable values from .txt file using C
問題描述
我用 C 編程的經驗有限，但由於軟件限制不得不使用這種語言。 我正在嘗試為 CFD 軟件編寫用戶自定義。
軟件在計算過程中寫入一個輸出文件，我想監視變量“PERCENT FILLED”並在值穩定時終止模擬。 我可以終止代碼，我遇到的問題是使用 C 讀取 PERCENT FILLED 的值，我可以在 python 或 shell 腳本中輕松完成此操作，但我真的很喜歡 C。
可能有一種更優雅的方法來做到這一點，我很高興學習，但我不是一個有經驗的程序員，所以我可能會迷失在復雜的解決方案中。
我試圖通過將任務分解為更小的子任務來做到這一點。 代碼的效率並不重要，因為此函數不必頻繁運行，而且要讀取的文件不是很大。 我相信有更快更優雅的方法來做到這一點！ 使用來自網絡的其他代碼並修改它們，我想出了以下內容。
我嘗試執行以下子任務：A）剝離包含“PERCENT FILLED”的所有行並將它們寫入文件（PERCENT FILLED.txt）B）讀取此文件中的行數，然后將最后 3 行讀入單獨的變量。 C) 然后我需要重新格式化這些變量。 例如，將 3 個變量從“PERCENT FILLED = 6.72902E+00”形式的字符串更改為浮點數，例如 6.72902。
我已經完成了 A)，在 B) 中有錯誤，並且不知道從哪里開始 C)。
B) 中的錯誤 - 當我運行代碼時，它會在 while 循環中正確地為 line1、line2 和 line3 分配值，但是一旦在 while 循環之外，所有值都會更改為 line1 的值。 這我不明白。 誰能幫我理解和解決這個問題？
示例代碼輸出：
line3: PERCENT FILLED = 6.31275E+00
line2: PERCENT FILLED = 6.50146E+00
line1: PERCENT FILLED = 6.72902E+00
******************
out line1: PERCENT FILLED = 6.72902E+00
out line2: PERCENT FILLED = 6.72902E+00
out line3: PERCENT FILLED = 6.72902E+00
C部分） - 我不知道從哪里開始。 看起來有足夠的內聯信息可以使用 atof() 將字符串轉換為浮點數。 但是，我首先需要從字符串的開頭刪除 PERCENT FILLED = ，然后轉換工程編號格式（有些值為 1.00E+02 所以簡單地去除最后 4 個字符 - E+00 - 將不起作用）。 這我不知道該怎么做。 任何幫助，將不勝感激。
示例輸入文件（通過刪除 PERCENT FILLED 值之間的 may 行來簡化）：
Step = 171 Iteration = 0 Time step = 0.014849 Time = 4.834002
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 4 1.0000000E+00 0.007999 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 5.46882E+00
Step = 172 Iteration = 0 Time step = 0.029698 Time = 4.863700
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 11 1.0000000E+00 0.018997 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 5.70902E+00
Step = 173 Iteration = 0 Time step = 0.029698 Time = 4.893398
Time step reduced by COURANT limit in free_surface, c_lim = 2.032750e-02
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 6 1.0000000E+00 0.010998 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 5.89665E+00
Step = 174 Iteration = 0 Time step = 0.020328 Time = 4.904356
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 7 1.0000000E+00 0.011997 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 6.08026E+00
Step = 175 Iteration = 0 Time step = 0.040655 Time = 4.945011
Time step reduced by COURANT limit in free_surface, c_lim = 2.547617e-02
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 9 1.0000000E+00 0.016998 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 6.31275E+00
Step = 176 Iteration = 0 Time step = 0.025476 Time = 4.955307
Time step reduced by COURANT limit in free_surface, c_lim = 1.997734e-02
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 9 1.0000000E+00 0.016994 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 6.50146E+00
Step = 177 Iteration = 0 Time step = 0.039955 Time = 4.989764
Time step reduced by COURANT limit in free_surface, c_lim = 2.547537e-02
Iter Variable Solver Loops Delta Solve CPU Form CPU
0 F EXPLC 13 1.0000000E+00 0.024994 0.000000
FRACTION SOLID = 0.000000e+00 %
PERCENT FILLED = 6.72902E+00
我目前的代碼：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
char line[1000];
char *pch;
char c[] = "PERCENT FILLED =";
char buff[1000];
/* Create a list of PERCENT FILLED values and write to file - copy every line containing PERCENT FILLED from p.out file*/
FILE *fp = fopen("inputFILE.txt", "r");
FILE *op = fopen("PERCENT_FILLED.txt", "w");
if(fp == NULL || op == NULL)
{
fprintf(stderr, "Error opening file.");
exit(1);
}
else
{
while (fgets(line, sizeof(line), fp) != 0)
{
if((pch = strstr (line, c))!= 0)
fprintf(op, "%s", line);
}
}
fclose(fp);
fclose(op);
/* Get the total number of lines in the file PERCENT_FILLED.txt */
FILE* myfile = fopen("PERCENT_FILLED.txt", "r");
int ch, number_of_lines = 0;
int line_num = 0;
int count = 0;
char readline[256]; /* or other suitable maximum line size */
char* line1;
char* line2;
char* line3;
do
{
ch = fgetc(myfile);
if(ch == '\n')
number_of_lines++;
} while (ch != EOF);
// last line doesn't end with a new line!
// but there has to be a line at least before the last line
if(ch != '\n' && number_of_lines != 0)
number_of_lines++;
fclose(myfile);
/* Get the last 3 PERCENT_FILLED values from the PERCENT_FILLED.txt */
FILE* infile = fopen("PERCENT_FILLED.txt", "r");
if ( infile != NULL )
{
while (fgets(readline, sizeof line, infile) != NULL) /* read a line */
{
if (count == (number_of_lines-4))
{
line3 = readline;
count++;
printf("\nline3:%s", line3);
}
else if (count == (number_of_lines-3))
{
line2 = readline;
count++;
printf("line2:%s", line2);
}
else if (count == (number_of_lines-2))
{
line1 = readline;
count++;
printf("line1:%s", line1);
}
else
{
count++;
printf("readline:%s count:%d\n", readline, count);
}
}
fclose(infile);
}
printf("******************\n");
printf("out line1:%s", line1);
printf("out line2:%s", line2);
printf("out line3:%s\n\n", line3);
/* strip "PERCENT FILLED = " from the string and turn the string into a float */
/* Do this for line1, line2, line3 */
/* Example string is " PERCENT FILLED = 6.72902E+00" need to turn this in to a float variable of value 6.72902 */
return 0;
}
1 個解決方案
解決方案1
1 2016-09-15 03:19:40
感謝您的幫助，我現在的代碼如下所示。 我確信有一種更優雅的方法可以做到這一點，但為了完整起見，我將提供我的最終代碼，以防它可以幫助某人。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
char line[1000];
char *pch;
char c[] = "PERCENT FILLED =";
char buff[1000];
/* Create a list of PERCENT FILLED values and write to file - copy every line containing PERCENT FILLED from p.out file*/
FILE *fp = fopen("inputFILE.txt", "r");
FILE *op = fopen("PERCENT_FILLED.txt", "w");
if(fp == NULL || op == NULL)
{
fprintf(stderr, "Error opening file.");
exit(1);
}
else
{
while (fgets(line, sizeof(line), fp) != 0)
{
if((pch = strstr (line, c))!= 0)
fprintf(op, "%s", line);
}
}
fclose(fp);
fclose(op);
/* Get the total number of lines in the file PERCENT_FILLED.txt */
FILE* myfile = fopen("PERCENT_FILLED.txt", "r");
int ch, number_of_lines = 0;
int line_num = 0;
int count = 0;
char readline[256]; /* or other suitable maximum line size */
char line1[256];
char line2[256];
char line3[256];
do
{
ch = fgetc(myfile);
if(ch == '\n')
number_of_lines++;
} while (ch != EOF);
// last line doesn't end with a new line!
// but there has to be a line at least before the last line
if(ch != '\n' && number_of_lines != 0)
number_of_lines++;
fclose(myfile);
/* Get the last 3 PERCENT_FILLED values from the PERCENT_FILLED.txt */
FILE* infile = fopen("PERCENT_FILLED.txt", "r");
if ( infile != NULL )
{
while (fgets(readline, sizeof line, infile) != NULL) /* read a line */
{
if (count == (number_of_lines-4))
{
strcpy ( line3, readline);
count++;
}
else if (count == (number_of_lines-3))
{
strcpy ( line2, readline);
count++;
}
else if (count == (number_of_lines-2))
{
strcpy ( line1, readline);
count++;
}
else
{
count++;
}
}
fclose(infile);
}
/* strip "PERCENT FILLED = " from the string and turn the string into a float */
/* Do this for line1, line2, line3 */
/* Example string is " PERCENT FILLED = 6.72902E+00" need to turn this in to a float varaible of value 6.72902 */
char per1[7], fil1[6], eq1[1];
char per2[7], fil2[6], eq2[1];
char per3[7], fil3[6], eq3[1];
float value1, value2, value3;
sscanf (line1, "%s %s %s %E", per1, fil1, eq1, &value1 );
sscanf (line2, "%s %s %s %E", per2, fil2, eq2, &value2 );
sscanf (line3, "%s %s %s %E", per3, fil3, eq3, &value3 );
printf("Value1: %f\n", value1 );
printf("Value2: %f\n", value2 );
printf("Value3: %f\n", value3 );
return 0;
}
使用 fscanf 將值從 .txt 文件讀取到 C 中的動態分配數組時出現訪問沖突錯誤？
[英]Access Violation error when using fscanf to read values from .txt file into a dynamically allocated array in C?
如何在 C 中使用 fscanf 從 txt 文件中讀取類似數據的句子？
[英]How to read sentence like data from txt file using fscanf in C?
聲明:本站的技術帖子網頁，遵循CC BY-SA 4.0協議，如果您需要轉載，請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.