20131005【C言語】ファイルの中身を交換する
お題
ファイルの中身を交換する
ソース
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
FILE *fp1, *fp2, *fptemp;
char ch;
/* Check arg count */
if (argc != 3) {
fprintf(stderr, "Usage: <Program Name> <File1> <File2>.\n");
exit(1);
}
/* Open File1 for read */
if *1 == NULL) {
fprintf(stderr, "Error while opening %s for reading.\n", argv[1]);
exit(1);
}
/* Open File2 for read */
if *2 == NULL) {
fprintf(stderr, "Error while opening %s for reading.\n", argv[2]);
exit(1);
}
/* Open temp file */
if *3 == NULL) {
fprintf(stderr, "Error while opening temp file.\n");
exit(1);
}
/* Copy from FILE1 to temp */
while(!feof(fp1)) {
ch = fgetc(fp1);
if (ferror(fp1)) {
fprintf(stderr, "Error while reading %s.\n", argv[1]);
exit(1);
}
if (!feof(fp1))
fputc(ch, fptemp);
if (ferror(fptemp)) {
fprintf(stderr, "Error while writing to temp file from %s.\n", argv[1]);
exit(1);
}
}
/* Close FILE1 */
if (fclose(fp1) == EOF) {
fprintf(stderr, "Error closing %s readingr writing.\n", argv[1]);
exit(1);
}
/* Close temp file */
if (fclose(fptemp) == EOF) {
fprintf(stderr, "Error closing temp file after copy from %s.\n", argv[1]);
exit(1);
}
/* Open FILE1 for write */
if *4 == NULL) {
fprintf(stderr, "Error while opening %s for writing.\n", argv[1]);
exit(1);
}
/* Copy from FILE2 to FILE1 */
while(!feof(fp2)) {
ch = fgetc(fp2);
if (ferror(fp2)) {
fprintf(stderr, "Error while reading %s.\n", argv[2]);
exit(1);
}
if (!feof(fp2))
fputc(ch, fp1);
if (ferror(fp1)) {
fprintf(stderr, "Error while writing to %s from %s.\n", argv[1], argv[2]);
exit(1);
}
}
/* Close FILE1 */
if (fclose(fp1) == EOF) {
fprintf(stderr, "Error closing %s after wriging from %s.\n", argv[1], argv[2]);
exit(1);
}
/* Close FILE2 */
if (fclose(fp2) == EOF) {
fprintf(stderr, "Error closing %s after copy from %s.\n", argv[2], argv[1]);
exit(1);
}
/* Open FILE2 for write */
if *5 == NULL) {
fprintf(stderr, "Error while opening %s for writing.\n", argv[2]);
exit(1);
}
/* Open temp file for read */
if *6 == NULL) {
fprintf(stderr, "Error while opening temp file for reading.\n");
exit(1);
}
/* Copy from temp file to FILE2 */
while(!feof(fptemp)) {
ch = fgetc(fptemp);
if (ferror(fptemp)) {
fprintf(stderr, "Error while reading temp file.\n");
exit(1);
}
if (!feof(fptemp))
fputc(ch, fp2);
if (ferror(fptemp)) {
fprintf(stderr, "Error while writing to %s from temp file.\n", argv[2]);
exit(1);
}
}
/* Close FILE2 */
if (fclose(fp2) == EOF) {
fprintf(stderr, "Error closing %s after wriging from temp file.\n", argv[2]);
exit(1);
}
/* Close temp file */
if (fclose(fptemp) == EOF) {
fprintf(stderr, "Error closing temp file after copy from temp file.\n");
exit(1);
}
exit(0);
}
実行結果
# cat file1.txt
This file is file1.
# cat file2.txt
This file is file2.
# ./a.out file1.txt file2.txt
# cat file1.txt
This file is file2.
# cat file2.txt
This file is file1.
