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我在C语言中编程经验有限，但由于软件限制，必须使用此语言。我正在尝试为CFD软件编写用户定制。如何从.txt文件中读取最后3个变量值，使用C
软件在计算过程中写入输出文件，我想监视变量“PERCENT FILLED”并在值稳定时终止模拟。我可以做代码的终止，我遇到的问题是使用C读取PERCENT FILLED的值，我可以很容易地在python或shell脚本中执行此操作，但是我真的在C中挣扎。
可能有这是一个非常优雅的方式，我很高兴学习，但我不是一个有经验的程序员，所以我可能会因为复杂的解决方案而迷失方向。
我试图通过将任务分解为更小的子任务来做到这一点。代码的效率并不重要，因为此函数不必频繁运行，并且要读取的文件不是很大。我相信有这样做更快，更优雅的方式！ 从网络使用其他代码并修改它们我已经拿出了下面的代码。
我试着做下面的子任务： A）剥去含有“PERCENT装”的所有行，并将它们写入文件（百分比FILLED.txt） B）阅读本文件的行数，然后读最后3行分成不同的变量。 C）然后我需要重新格式化这些变量。例如，将3个变量从“PERCENT FILLED = 6.72902E + 00”形式的字符串更改为诸如6.72902等值的浮点数。
我已经完成了A），在B）中有错误，并且无法确定从哪里开始C）。
B）中的错误 - 当我运行代码时，它正确地为while循环中的line1，line2和line3赋值，但是一旦在while循环外，所有值都变为line1的值。这我不明白。任何人都可以帮我理解并解决这个问题吗
示例代码输出：
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） - 我不知道从哪里开始与此有关。它看起来有足够的信息内联使用atof（）将字符串转换为浮点数。但是，我首先需要从字符串的起始处删除PERCENT FILLED =，然后转换工程编号格式（某些值为1.00E + 02，因此仅删除最后4个字符--E + 00 - 将不起作用）。这我不知道该怎么做。任何帮助，将不胜感激。
实施例输入文件（通过去除PERCENT填充的值之间可能线而简化）：
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
我当前的代码：
#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;
}
见'人sscanf'，从字符串读取，让您将通过一个格式说明和可变的数据等，然后格式化从变量的输出。 – KevinDTimm