write in a file next line each time

[muskan]

hello,

In my code i opened a file and write in it now i want each time i reopen it,data must be written from next line.
my code snippet is:

unsigned char buffer[8]={0};
int cmd=1;
int tt=100;
tt<<16;
tt|cmd;
sprintf((char*)buffer,"%d",tt);
FILE *fp;
fp=fopen("root/test.txt","a");
if(fp==NULL)
perror("file pointer:");
fwrite(buffer 8,1,fp);
fclose(fp);

unsigned char buffer[8]={0};
int cmd=1;
int tt=100;
tt<<16;
tt|cmd;
sprintf((char*)buffer,"%d",tt);
FILE *fp;
fp=fopen("root/test.txt","a");
if(fp==NULL)
perror("file pointer:");
fwrite(buffer 8,1,fp);
fclose(fp);

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I also searched but did'nt got any right answer. I want my new text will come at the beginning of next line each time i write. please help me out.
Thanks in advance

[Lykurg]

Why don't you use the Qt classes like QFile for your task? Also see QIODevice::Append.

[ChrisW67]

If you want basic C programming help then a Qt specific forum is not the best place to look.

If you want a text file with new line characters between lines then you should actually put a new line character in the output and use the text file write functions like fprintf() (or C++ streams).

int tt=100;
FILE *fp = NULL;
if (fp = fopen("test.txt", "a")) {
    fprintf(fp, "%d\n", tt);
}

int tt=100;
FILE *fp = NULL;
if (fp = fopen("test.txt", "a")) {
    fprintf(fp, "%d\n", tt);
}

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or using Qt:

int tt=100;
 
QFile fp("test.txt");
 
if (fp.open(QIODevice::Text | QIODevice::Append)) {
    QTextStream s(&fp);
    s << tt << endl;
}

int tt=100;

QFile fp("test.txt");

if (fp.open(QIODevice::Text | QIODevice::Append)) {
    QTextStream s(&fp);
    s << tt << endl;
}

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Unrelated to your question:

• Lines 4 and 5 do nothing (generate compiler warnings here)
• Line 11 will not compile as supplied, and the arguments are possibly the wrong way around.