如何在C中每3个字符后添加一个换行符?
我有一个包含以下内容的文本文件“123.txt”: 123456789 我希望输出为: 123如何在C中每3个字符后添加一个换行符?,c,file,newline,C,File,Newline,我有一个包含以下内容的文本文件“123.txt”: 123456789 我希望输出为: 123 456 789 这意味着,每3个字符后必须插入一个换行符 void convert1 (){ FILE *fp, *fq; int i,c = 0; fp = fopen("~/123.txt","r"); fq = fopen("~/file2.txt","w"); if(fp == NULL) printf("Error in opening
456
789 这意味着,每3个字符后必须插入一个换行符
void convert1 (){
FILE *fp, *fq;
int i,c = 0;
fp = fopen("~/123.txt","r");
fq = fopen("~/file2.txt","w");
if(fp == NULL)
printf("Error in opening 123.txt");
if(fq == NULL)
printf("Error in opening file2.txt");
while (!feof(fp)){
for (i=0; i<3; i++){
c = fgetc(fp);
if(c == 10)
i=3;
fprintf(fq, "%c", c);
}
if(i==4)
break;
fprintf (fq, "\n");
}
fclose(fp);
fclose(fq);
}
void convert1(){
文件*fp,*fq;
int i,c=0;
fp=fopen(“~/123.txt”,“r”);
fq=fopen(“~/file2.txt”,“w”);
如果(fp==NULL)
printf(“打开123.txt时出错”);
如果(fq==NULL)
printf(“打开文件2.txt时出错”);
而(!feof(fp)){
对于(i=0;i,如注释所示,您的while
循环不正确。请尝试将您的while
循环与以下代码交换:
i = 0;
while(1)
{
// Read a character and stop if reading fails.
c = fgetc(fp);
if(feof(fp))
break;
// When a line ends, then start over counting (similar as you did it).
if(c == '\n')
i = -1;
// Just before a "fourth" character is written, write an additional newline character.
// This solves your main problem of a newline character at the end of the file.
if(i == 3)
{
fprintf(fq, "\n");
i = 0;
}
// Write the character that was read and count it.
fprintf(fq, "%c", c);
i++;
}
示例:包含以下内容的文件:
12345
123456789
已转换为包含以下内容的文件:
123
45
123
456
789
我认为你应该在lopp的乞讨处生产你的新产品:
// first read
c = fgetc(fp);
i=0;
// fgetc returns EOF when end of file is read, I usually do like that
while((c = fgetc(fp)) != EOF)
{
// Basically, that means "if i divided by 3 is not afloating number". So,
// it will be true every 3 loops, no need to reset i but the first loop has
// to be ignored
if(i%3 == 0 && i != 0)
{
fprintf (fq, "\n");
}
// Write the character
fprintf(fq, "%c", c);
// and increase i
i++;
}
我现在无法测试它,可能有一些错误,但你明白我的意思。而(!feof(fp))
是。@melpomene你能详细说明一下吗?@Sebi:仔细阅读它的作用,然后进一步阅读并思考其含义。如果没有帮助,请阅读由melpomene链接的问答。