How can I pass an array of structures to another function - c

Question

I am trying to pass an array of structs as pointer in another function. But the compiler just refuses.
I build up this code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Values{
char timestamp[21];
char temperature[2];
int tmp;
};
char *readString(char out[], FILE *fp){// Reading and storing the input values, out = the string that this func returns
int ch, i;
while(EOF!=(ch=fgetc(fp)))
if(ch == '"') break;
for(i=0;EOF!=(ch=fgetc(fp));++i){
if(ch == '"') break;
out[i] = ch;
}
out[i]='\0';
return out;
}
void printValues(struct Values * v, int i){ //just a printing method, for printing the values, i = the amount of values I have
int j;
for(j=0; j<i; j++){
printf("%s \t : \t %s \t :\t %d \n\n", v[j]->timestamp, v[j]->temperature, v[j]->tmp);
}
}
void makeTmpIntegers(struct Values values[], int i){ //making temperatures integers so I can use them in sorts, i = the amount of values I have
int j;
for(j=0; j<i;j++){
values[j].tmp = atoi(values[j].temperature);
}
}
int main(void){ //The beginning of the programm, what did you expect?
struct Values values[8223];
FILE *file = fopen("hum.txt", "r" );
int i=0; //the number of every stored value (for the timestamps)
int k=0; //the number of every stored value (for the temperatures)
if (file != NULL ){
char tempString [21];
int flag = 1;
while(*readString(tempString, file)){ //if the readStrinf outputs "/0" == "" (end of FILE)
if(flag == 1){strcpy(values[i].timestamp, tempString); flag++; i++;}
else if(flag == 2){strcpy(values[k].temperature, tempString); flag--; k++;}
}
fclose(file);
}
makeTmpIntegers(values, i);
printValues(&values, i);
return 0;
}
I know for a fact that I can pass the struct from a function to another (it works fine that way), but I want to pass pointers (memory reasons).
I have been trying to do it at the function called printValues()
In this case the compiler does not compile. This is the message I get:
In function 'printValues':
24 46 [Error] invalid type argument of '->' (have 'struct Values')
24 63 [Error] invalid type argument of '->' (have 'struct Values')
24 82 [Error] invalid type argument of '->' (have 'struct Values')
In function 'main':
53 17 [Warning] passing argument 1 of 'printValues' from incompatible pointer type
21 6 [Note] expected 'struct Values *' but argument is of type 'struct Values (*)[8223]'
Plus if I initialize the function like this: void printValues(struct Values * v[], int i)
It does compile but it does not prints the values at all
I know that the correct way to read an integer from a txt file, is not like this but I couldn't figure something else out

Answer 1

This is OK:
struct Values{
char timestamp[21];
char temperature[2];
int tmp; };
So are these two function signatures:
void printValues(struct Values * v, int i) { ... }
void makeTmpIntegers(struct Values values[], int i) { ... }
This is WRONG:
v[j]->timestamp, v[j]->temperature, ...
Substitute:
v[j].timestamp, v[j].temperature, ...
ALSO:
Change printValues(&values, i); to printValues(values, i);
I haven't checked carefully for any other errors, but this should get you moving in the right direction...
ADDENDUM:
In both of the examples above, printValues(struct Values * v, int i) and makeTmpIntegers(struct Values values[], int i), you're ALREADY "passing by pointer". You just need to fix your syntax, as in my examples.
As Oppen said below:
Also, note that passing an array argument in C is functionally
equivalent to passing a pointer, no copy is involved, so I'm not sure
what memory reasons stop you from just passing the array of structs
directly...