我有一个输入文件，是这样的，这是第1行.第2行.第3行:
这是第1行，第2行，第3行。
我需要输出的文件是这样的
OddLines.txt。
这是第一行，这是第三行。
EvenLines.txt: 这是第1行.这是第3行.EvenLines:
这是第二行。
这是我的代码。但没有达到我想要的效果。
char buf[256];
int ch;
int lines;
lines = 1;
FILE *myFile = fopen(argv[1], "r");
if (myFile == NULL) {
printf("Open error \n");
exit(-1);
}
FILE *outFile = fopen("oddlines.txt", "w");
FILE *outFile1 = fopen("evenlines.txt", "w");
while (fgets(buf, sizeof(buf), myFile) != NULL) {
if (ch == '\n')
lines++;
else
if ((lines % 2) == 0)
fputs(buf, outFile1);
else
fputs(buf, outFile);
}
fclose(myFile);
fclose(outFile);
fclose(outFile1);
}
不清楚你是想让输出文件包含输入文件中的行，还是想让这些行必须被连接起来，去掉新行。
你的代码不工作，因为测试 if (ch == '\n') 具有未定义的行为，如 ch 是未初始化的。因此，行计数器没有正确更新，所有的行都进入了其中一个文件。
实际上，计算行数并不像计算循环的迭代那样简单，因为输入文件中的一些行数可能比 fgets(). 你应该在写完后更新行计数器，测试刚刚写的行是否真的包含一个换行符。
这里是一个修改后的版本。
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[]) {
char buf[256];
int lines = 1;
FILE *myFile, *outFile, *outFile1;
if (argc < 2) {
printf("Missing argument\n");
return 1;
}
if ((myFile = fopen(argv[1], "r")) == NULL) {
printf("Open error for %s\n", argv[1]);
return 1;
}
if ((outFile = fopen("oddlines.txt", "w")) == NULL) {
printf("Open error for %s\n", "oddlines.txt");
return 1;
}
if ((outFile1 = fopen("evenlines.txt", "w")) == NULL) {
printf("Open error for %s\n", "evenlines.txt");
return 1;
}
while (fgets(buf, sizeof(buf), myFile) != NULL) {
if (lines % 2 == 0)
fputs(buf, outFile1);
else
fputs(buf, outFile);
/* if a full line was read, increment the line number */
if (strchr(buf, '\n')
lines++;
}
fclose(myFile);
fclose(outFile);
fclose(outFile1);
return 0;
}
下面是一个更简单的版本，它没有使用 fgets():
#include <stdio.h>
int main(int argc, char *argv[]) {
int c, out;
FILE *myFile, *outFile[2];
if (argc < 2) {
printf("Missing argument\n");
return 1;
}
if ((myFile = fopen(argv[1], "r")) == NULL) {
printf("Open error for %s\n", argv[1]);
return 1;
}
if ((outFile[0] = fopen("oddlines.txt", "w")) == NULL) {
printf("Open error for %s\n", "oddlines.txt");
return 1;
}
if ((outFile[1] = fopen("evenlines.txt", "w")) == NULL) {
printf("Open error for %s\n", "evenlines.txt");
return 1;
}
out = 0; /* current output file is "oddlines.txt" */
while ((c = getc(myFile)) != EOF) {
putc(c, outFile[out]);
if (c == '\n')
out = 1 - out; /* change current output file */
}
fclose(myFile);
fclose(outFile[0]);
fclose(outFile[1]);
return 0;
}
如果你想从第三个输出文件中去掉元音，只需在文件中加入 <string.h>，打开该文件，以 FILE *noVowelFile 并在 while 循环。
out = 0; /* current output file is "oddlines.txt" */
while ((c = getc(myFile)) != EOF) {
if (strchr("aeiouAEIOU", c) == NULL) {
putc(c, noVowelFile);
}
putc(c, outFile[out]);
if (c == '\n')
out = 1 - out; /* change current output file */
}
if (ch == '\n')
这段代码没有意义. 你想找到回车符吗？如果是，你可以使用 strcspn 职能。
int pos = strcspn ( buf, "\n" );
职能： lines 应通过以下方式初始化 0 不 1:
int lines = 0;
while(fgets(buf, sizeof(buf),myFile))
{
lines++;
int pos = strcspn ( buf, "\n" ); // find the enter character
buf[pos] = ' '; // add space at the end of string
buf[pos+1] = '\0';
if ((lines%2)==0) // if even
fputs (buf,outFile1);
else // if odd
fputs (buf,outFile);
}
你应该检查一下 fopen 功能。
FILE *myFile = fopen(argv[1], "r");
if(!myFile) {return -1;}
FILE *outFile = fopen("oddlines.txt", "w");
if(!outFile) {return -1;}
FILE *outFile1 = fopen("evenlines.txt", "w");
if(!outFile1) {return -1;}
和命令行的条件。
if(argc < 2 ) {
printf("usage: %s <input_filename>", argv[0]);
return-1;
}
完整的代码：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char const *argv[]) {
char buf[256];
int lines = 0;
if(argc < 2 ) {
printf("usage: %s <input_filename>", argv[0]);
return-1;
}
FILE *myFile = fopen(argv[1], "r");
if(!myFile) {return -1;}
FILE *outFile = fopen("oddlines.txt", "w");
if(!outFile) {return -1;}
FILE *outFile1 = fopen("evenlines.txt", "w");
if(!outFile1) {return -1;}
while(fgets(buf, sizeof(buf),myFile)!=NULL)
{
lines++;
int pos = strcspn ( buf, "\n" );
buf[pos] = ' ';
buf[pos+1] = '\0';
if ((lines%2)==0)
fputs (buf,outFile1);
else
fputs (buf,outFile);
}
fclose(myFile);
fclose(outFile);
fclose(outFile1);
}
输入文件：
This is 1nd Line.
This is 2nd Line.
This is 3rd Line.
This is 4th Line.
This is 5th Line.
This is 6th Line.
输出文件：
$cat evenlines.txt
This is 2nd Line. This is 4th Line. This is 6th Line.
$cat oddlines.txt
This is 1nd Line. This is 3rd Line. This is 5th Line.
if (ch == '\n')
问题就出在这一行
#include <stdio.h>
#include<string.h>
void main()
{
int line=1;
char buf[256];
FILE *fp, *fp_Odd, *fp_Even;
fp=fopen("USERS.TXT", "r");
fp_Odd=fopen("ODD.TXT", "a");
fp_Even=fopen("EVEN.TXT", "a");
if(fp == NULL)
{
printf("Open error \n");
exit(-1);
}
while(fgets(buf, sizeof(buf), fp)!=NULL)
{
if(strcmp(buf, "\n")==0)
line++;
else if(line%2 != 0)
fprintf(fp_Odd, "%s", buf);
else
fprintf(fp_Even, "%s", buf);
line++;
}
fclose(fp);
}
你可以检查这段代码。我已经做了必要的修改。希望你能理解。