I would like to understand how to write to a file, numbers from 0 to 10, from this code:
main(){
setlocale(LC_ALL,"Portuguese");
int num[10],i;
FILE *arquivo;
arquivo = fopen("c:\Ling_C\resultado.txt","a");
if(arquivo==NULL){
printf("Arquivo texto.txt não pode ser aberto!\n");
getchar();
}
else{
for (i=0;i<10;i++){
fwrite(&num[i],sizeof(int),10,arquivo);
}
}
fclose(arquivo);
getchar();
}
First the bar is reversed in the path of the file.
According to the fopen function, the parameters
fopen("file", **a**) indicates that it will concatenate at the end of the file, use the
fopen("file", **w**) if you want to overwrite.
For writing to files you can use the function fprintf , follow the link with definition of some functions for writing in files:
The functions fputc (), fprintf () and fputs ()
See the example below and then its output:
#include <stdio.h>
#include <conio.h>
int main(void){
FILE *arq;
int result;
arq = fopen("C:/Users/inpart/Desktop/EstudoC/ArqGrav.txt", "w");
if (arq == NULL)
{
printf("Arquivo ArqGrav.txt não pode ser aberto!\n");
return 0;
}
for (int i = 0; i<10;i++)
{
fprintf(arq,"Linha %d\n", i);
}
fclose(arq);
return 0;
}
The @CaiqueRomero response attacked the problem on the one hand that I consider unexpected, but very good. He also talks about all the other things about opening files and left great reading references.
I came here to talk about fwrite .
The first thing is to see the function signature:
size_t fwrite ( const void * ptr, size_t size, size_t count, FILE * stream );
Okay, let's understand what that means. The function says that it will print in stream passed% with% elements of size count pointed to size_t .
If you want to print ten integers of a ptr vector in the v file, you could do:
fwrite(v, sizeof(int), 10, f);
Where:
f is the vector, so it can be worked as a pointer v is the size of the vector unit; could also be sizeof(int) or sizeof(*v) , but I'd rather pass the type sizeof(v[0]) is the number of elements 10 is the file open for writing Some comments:
f writes bytes, literally fwrite writes the textual representation fprintf is going to be used, and it usually opens in textual mode to fwrite for performance issues
fprintf as argument of rb ; write is with fopen
wb , you'll get a result like this (credits to @ CaiqueRomero by print): 