# slow5_init_batch
## NAME
slow5_init_batch - initialises a slow5 record batch
## SYNOPSYS
`slow5_batch_t* slow5_init_batch(int batch_capacity)`
## DESCRIPTION
`slow5_init_batch()` function initialises and returns a batch of empty SLOW5 records. The number of empty records in the batch will be what is specified by *batch_capacity*. The returned SLOW5 record batch must be later freed by calling `slow5_free_batch()`.
## RETURN VALUE
Upon successful completion, `slow5_init_batch()` returns a *slow5_batch_t* pointer.
## ERRORS
Currently, in case of error, this function will exit the programme. Proper error handling might be introduced in future, where a NULL return is indicative of error.
## EXAMPLES
```
#include <stdio.h>
#include <stdlib.h>
#include <slow5/slow5.h>
#include <slow5/slow5_mt.h>
#define FILE_PATH "examples/example.slow5"
int main(){
slow5_file_t *sp = slow5_open(FILE_PATH,"r");
if(sp==NULL){
fprintf(stderr,"Error in opening file\n");
exit(EXIT_FAILURE);
}
int batch_size = 4096;
int num_thread = 8;
slow5_mt_t *mt = slow5_init_mt(num_thread,sp);
if (mt==NULL){ //currently not useful, but better have this for future proofing
fprintf(stderr,"Error in initialising multi-thread struct\n");
exit(EXIT_FAILURE);
}
slow5_batch_t *read_batch = slow5_init_batch(batch_size);
if (read_batch==NULL){ //currently not useful, but better have this for future proofing
fprintf(stderr,"Error in initialising slow5 record batch\n");
exit(EXIT_FAILURE);
}
// ...
slow5_free_batch(read_batch);
slow5_free_mt(mt);
slow5_close(sp);
return 0;
}
```
## SEE ALSO
[slow5_free_batch()](slow5_free_batch.md)