This question already has answers here:
How do I pass an array of structures to a function?
(3 answers)
Closed 1 year ago.
About to ready to give up on this
Been having an issue with my code for hours, has been telling me I have an error about the error: expected expression before 'Robot_t' and cannot find a solution, if anyone has a working solution you will save me
This is the error message provided
Arrayintofn.c: In function 'main':
Arrayintofn.c:23:23: error: expected expression before 'Robot_t'
loading_Profiles (Robot_t RobotInfo[]);
No matter what I do or who I consult there is no solution
Here is the code as well
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <string.h>
typedef struct
{
int Robot_Number;
char Robot_Name[30];
int Year_Manufacturer;
float Top_Speed;
float Mass;
float Best_Score;
} Robot_t;
void loading_Profiles();
int main()
{
Robot_t RobotInfo[5];
loading_Profiles (Robot_t RobotInfo[]);
int i;
for (i = 0; i < 50; i++) {
printf("%d\t\t%s\t\t%d\t\t\t%.2f\t\t%.2f\t\t%.2f\n",
RobotInfo[i].Robot_Number, RobotInfo[i].Robot_Name,
RobotInfo[i].Year_Manufacturer, RobotInfo[i].Top_Speed,
RobotInfo[i].Mass, RobotInfo[i].Best_Score);
}
return 0;
}
void loading_Profiles()
{
int Counter = 0;
int i;
Robot_t RobotInfo[5];
FILE *ROBOTtxt = fopen("Robot.txt", "r");
if (ROBOTtxt == NULL) {
perror("an error occured during the loading of the file\n");
exit(-1);
}
for (i = 0; i < 50; i++) {
char LineNumber[100] = "";
fgets(LineNumber, 100, ROBOTtxt);
sscanf(LineNumber, "%d %s %d %f %f %f",
&RobotInfo[i].Robot_Number,
RobotInfo[i].Robot_Name,
&RobotInfo[i].Year_Manufacturer,
&RobotInfo[i].Top_Speed,
&RobotInfo[i].Mass,
&RobotInfo[i].Best_Score);
Counter++;
if (feof(ROBOTtxt)) {
break;
}
}
if (ferror(ROBOTtxt)) {
perror("an error has occured");
exit(-1);
}
fclose(ROBOTtxt);
}
Your function loading_Profiles() written like this doesnt accept any parameters but you pass an array in the main function. You should rewrite the declaration as
"void loading_Profiles(Robot_t arr_name[])"
In the main function you should pass an argument only by its name. So instead of this:
"loading_Profiles(Robot_t RobotInfo[]);"
just pass:
"loading_Profiles(RobotInfo);"
There were a number of errors in your code, I'll paste my commented solution below, but for reference:
in the loading_Profiles prototype you weren't specifying a parameter
in the main, you were calling the function uncorrectly
inside the loading_Profiles implementation, you were trying to work on a local array, and not the one passed as an argument.
Also, sometimes you were using 50, sometimes 5? Which is it?
Here's the code, tested using a file generated on Mockaroo.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <string.h>
typedef struct
{
int Robot_Number;
char Robot_Name[30];
int Year_Manufacturer;
float Top_Speed;
float Mass;
float Best_Score;
} Robot_t;
void loading_Profiles(Robot_t RobotInfo[]); // added parameter to prototype
int main()
{
Robot_t RobotInfo[50]; // 50 instead of 5
loading_Profiles(RobotInfo); // simply pass your variable
int i;
for (i = 0; i < 50; i++) {
printf("%d\t\t%s\t\t%d\t\t\t%.2f\t\t%.2f\t\t%.2f\n",
RobotInfo[i].Robot_Number, RobotInfo[i].Robot_Name,
RobotInfo[i].Year_Manufacturer, RobotInfo[i].Top_Speed,
RobotInfo[i].Mass, RobotInfo[i].Best_Score);
}
return 0;
}
void loading_Profiles(Robot_t RobotInfo[]) // added parameter
{
int Counter = 0;
int i;
FILE *ROBOTtxt = fopen("Robot.txt", "r");
//Robot_t RobotInfo[5]; // removed, work on the array passed as argument, not a local one
if (ROBOTtxt == NULL) {
perror("an error occured during the loading of the file\n");
exit(-1);
}
for (i = 0; i < 50; i++) {
char LineNumber[100] = "";
fgets(LineNumber, 100, ROBOTtxt);
sscanf(LineNumber, "%d %s %d %f %f %f",
&RobotInfo[i].Robot_Number,
RobotInfo[i].Robot_Name,
&RobotInfo[i].Year_Manufacturer,
&RobotInfo[i].Top_Speed,
&RobotInfo[i].Mass,
&RobotInfo[i].Best_Score);
Counter++;
if (feof(ROBOTtxt)) {
break;
}
}
if (ferror(ROBOTtxt)) {
perror("an error has occured");
exit(-1);
}
fclose(ROBOTtxt);
}
Let me know if it works
While declaring parameter for the function you need to specify variable type as structure and create an array of structure type.
void loading_Profiles(Robot_t RobotInfo[]) // added parameter
Related
I'm trying to pass an array of structs to a function which fills them with data.
When I try to compile the code I am told that there is an error:
In function 'main':
error: expected expression before 'Robot_t'
loading_Profiles (Robot_t RobotInfo[]);
I am not sure what I am missing?
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <string.h>
typedef struct {
int Robot_Number;
char Robot_Name[30];
int Year_Manufacturer;
float Top_Speed;
float Mass;
float Best_Score;
} Robot_t;
void loading_Profiles();
int main()
{
Robot_t RobotInfo[5];
loading_Profiles (Robot_t RobotInfo[]);
int i;
for (i = 0; i < 50; i++) {
printf("%d\t\t%s\t\t%d\t\t\t%.2f\t\t%.2f\t\t%.2f\n",
RobotInfo[i].Robot_Number, RobotInfo[i].Robot_Name,
RobotInfo[i].Year_Manufacturer, RobotInfo[i].Top_Speed,
RobotInfo[i].Mass, RobotInfo[i].Best_Score);
}
return 0;
}
void loading_Profiles()
{
int Counter = 0;
int i;
Robot_t RobotInfo[5];
FILE *ROBOTtxt = fopen("Robot.txt", "r");
if (ROBOTtxt == NULL) {
perror("an error occured during the loading of the file\n");
exit(-1);
}
for (i = 0; i < 50; i++) {
char LineNumber[100] = "";
fgets(LineNumber, 100, ROBOTtxt);
sscanf(LineNumber, "%d %s %d %f %f %f",
&RobotInfo[i].Robot_Number,
RobotInfo[i].Robot_Name,
&RobotInfo[i].Year_Manufacturer,
&RobotInfo[i].Top_Speed,
&RobotInfo[i].Mass,
&RobotInfo[i].Best_Score);
Counter++;
if (feof(ROBOTtxt)) {
break;
}
}
if (ferror(ROBOTtxt)) {
perror("an error has occured");
exit(-1);
}
fclose(ROBOTtxt);
}
There are several issues with your program. The obvious one is that your function prototypes do not match:
void loading_Profiles()
should be
void loading_Profiles(Robot_t *robots)
in both the declaration and definition.
The array Robot_t RobotInfo[5] in main, and the Robot_t RobotInfo[5] in loading_Profiles do not refer to the same array. They are separate arrays, local to each function. You need to pass the array from main to the loading_Profiles function, which should then modify the array.
Your code also contains various size errors. You are defining an array of 5 elements, and then trying to read and write up to 50 elements. Beyond the mismatch, you need to think about what happens if your file contains less lines than expected.
Counter is unused. As are the return values of some functions that can indicate status / errors:
fgets already partially indicates if it has reached EOF by returning NULL.
sscanf returns the numbers of conversions that took place, which can be used to make sure a partial set of data wasn't stored.
Here is a rewritten example that showcases how to pass arrays around, fill them to a maximum, and utilize the return values of stdio functions. Notice how the type signature of load_robot_profiles matches exactly between the declaration, definition, and invocation of the function.
#include <stdio.h>
#include <stdlib.h>
typedef struct {
int number;
char name[32];
int year_manufactured;
float top_speed;
float mass;
float best_score;
} Robot;
size_t load_robot_profiles(Robot *, size_t, const char *);
int main(void) {
Robot robots[5];
size_t length = load_robot_profiles(robots, 5, "robots.txt");
for (size_t i = 0; i < length; i++) {
Robot *r = &robots[i];
printf("%d\t%s\t%d\t\t%.2f\t%.2f\t%.2f\n",
r->number, r->name, r->year_manufactured,
r->top_speed, r->mass, r->best_score);
}
}
size_t load_robot_profiles(Robot *robots, size_t size, const char *fname) {
size_t i = 0;
FILE *file = fopen(fname, "r");
char input[128];
if (!file)
return 0;
while (i < size && fgets(input, sizeof input, file)) {
Robot *r = &robots[i];
if (6 == sscanf(input, "%d %s %d %f %f %f",
&r->number, r->name, &r->year_manufactured,
&r->top_speed, &r->mass, &r->best_score))
i++;
}
fclose(file);
return i;
}
Also note: Defining a type with a _t suffix is ill-advised, as eventually you will brush up against a conflict with an existing POSIX type, or other standard.
Your definition and declaration of the function void loading_Profiles() don't include any arguments, but you're calling it with an argument: loading_Profiles (Robot_t RobotInfo[]);.
You need to change the function to accept Robot_t RobotInfo[] as an argument and then modify the RobotInfo[] array.
The function signature should be like that:
void loading_Profiles(Robot_t* RobotInfo);
Also, there is no need to redeclare the Robot_t RobotInfo[5] inside your loading_Profiles function, since it is already passed by the function call.
I'm passing a matrix to a text file
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int llenarMatriz() {
int matriz[3][3]={1,2,3,4,5,6,7,8,9};
return matriz[3][3];
}
void guardarMatriz(int matriz[3][3]) {
char direccion[]="C:\\Users\\Usuario\\Desktop\\DIBU.txt";
FILE *archivo = fopen(direccion, "w");
if (archivo == NULL) {
exit(EXIT_FAILURE);
}
char linea[20];
sprintf(linea, "%d %d\n", 3, 3);
fputs(linea, archivo);
for (int i = 0; i < 3; i++) {
linea[0] = '\0';
for (int j = 0; j < 3; j++){
char buffer[10];
sprintf(buffer, "%d ", matriz[3][3]);
strcat(linea, buffer);
}
int len = strlen(linea);
linea[len - 1] = '\n';
fputs(linea,archivo);
}
fclose(archivo);
}
int main() {
llenarMatriz();
guardarMatriz(int matriz[3][3]);
system("pause");
return 0;
}
Error message;
In function 'main':
error: expected expression before 'int'
guardarMatriz(int matriz[3][3]);
You have two problems in your code. First you don't initialize a 2-D array correctly. It should look like this:
int matriz[3][3]={{1,2,3},{4,5,6},{7,8,9}};
second, you don't pass a type name to the function call to declare your variable, so it should look like this:
int matriz[3][3];
llenarMatriz();
guardarMatriz(matriz);
guardarMatriz(int matriz[3][3]);
Don't include the type and the dimensions when passing parameters to a function.
Also, when you call a function returning something, you should use the correct type (an int is not able to return a 2D array of int), and you must store the return somewhere.
In this case you can return a compound literal:
void *llenarMatriz(void)
{
return (int [][3]){{1,2,3},{4,5,6},{7,8,9}};
}
and in main:
int main(void) /* void is the correct argument for `main` */
{
int (*matriz)[3] = llenarMatriz(); /* A pointer to an array of int 3 */
guardarMatriz(matriz);
system("pause");
return 0;
}
If you don't want to declare the array inside main you can use the result of the first function as the argument of the second one:
guardarMatriz(llenarMatriz());
or you can pass the compound literal directly:
guardarMatriz((int [][3]){{1,2,3},{4,5,6},{7,8,9}});
This question already has answers here:
Returning an array using C
(8 answers)
Closed 6 years ago.
I have to use the function to open a file, read it, save the first value as the number of following elements (dimension) and the other values in the seq[] array.
I don't know how to return both dimension and seq[] in the main; I need it because I have to use these values in other functions. As the code shows, the function returns the dimension (dim), but I don't know how to return the array.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
int leggiSequenza(char *nomeFile, int *seq) {
FILE *in;
int i;
int dim;
if((in = fopen(nomeFile, "r"))==NULL) {
printf("Error.\n");
return -1;
}
fscanf(in, "%d", &(dim));
printf("Find %d values.\n", dim);
if(dim < 0) {
printf("Errore: negative value.\n");
return -1;
}
seq = (int*) malloc(dim*sizeof(int));
i=0;
while(!feof(in) && i<(dim)) {
fscanf(in, "%d", &seq[i]);
i++;
}
for(i=0; i<(dim); i++) {
printf("Value in position number %d: %d.\n", i+1, seq[i]);
}
free(seq);
fclose(in);
return dim;
}
int main(int argc, char* argv[]) {
int letturaFile;
char nomeFile[200];
int *dimensione;
printf("Insert file name:\n");
scanf("%s", nomeFile);
printf("\n");
letturaFile = leggiSequenza(nomeFile, dimensione);
dimensione = &letturaFile;
printf("dimension = %d\n", *dimensione);
return 0;
}
I think the focus of the problem is *seq; I have to return two values (dimension and array). Moreover, I can't edit the parameters of the function.
I think my question is different from this because in my function there is a parameter with a pointer, and the function hasn't got a pointer...
Change the function to take the array pointer by pointer:
int leggiSequenza(char *nomeFile, int **seq);
// ^^^^^^^^^
Then call it with the address of your variable:
leggiSequenza(nomeFile, &dimensione);
// ^^^^^^^^^^^
Inside the function definition, change the details around like so:
int leggiSequenza(char *nomeFile, int **seq) {
// ...
int *local_seq = malloc(dim*sizeof(int));
// use local_seq in place of seq
// free(local_seq); // delete ...
*seq = localsec; // ... and replace with this
return dim;
}
Finally, the caller needs to free the array:
free(dimensione);
Update: Since you've re-asked your question: Pre-allocate the memory at the call site:
int * p = malloc(200 * sizeof(int));
int dim = leggiSequenza(filename, p);
// ...
free(p);
Simply your function should have this signature
int leggiSequenza(char *nomeFile, int **seq)
and when passing the parameter to it you should do
letturaFile = leggiSequenza(nomeFile, &dimensione);
that way, you'll have both things.
Also, everywhere in your function where you have just seq , you need to add *seq so you can dereference the pointer.
Hope this helps!
Do the alloction of the array in the main function
int *dimensione; = (int*) malloc(200*sizeof(int));
then delete this line
free(seq);
and you should have the data in the array in the main function.
I am trying to use the getStats function twice - once for each input file. I am supposed to be using a char array called statFile[]to pass as the argument to the prototype to select which file it is to work with. Currently I know how to use one file at a time (by explicit naming the file in the prototype) to make it work, but do not understand how to use it for both inputs. Thanks in advance!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define AUBURN "auburn2013.txt" //input data files
#define ALABAMA "alabama2013.txt" //input data files
#define NUMGAMES 13
int getStats( char statFile[], int compPass[], int attPass[], int numYds[], int numTD[] );
void analysis( int compPass[], int attPass[], int numYds[], int numTD[], double aveYds[], double pectCmp[], int tdPts[], int numGames[]);
int main(void)
{
int compPass[NUMGAMES],
attPass[NUMGAMES],
numYds[NUMGAMES],
numTD[NUMGAMES];
double bamaStats,
auburnStats,
setAuburn,
setBama;
FILE *au = fopen("auburn2013.txt","r");
FILE *al = fopen("alabama2013.txt","r");
if (al == NULL)
printf("Error Opening File\n");
else if (au == NULL)
printf("Error Opening File\n");
bamaStats = getStats(ALABAMA, compPass, attPass, numYds, numTD);
return 0;
}
int getStats( char statFile[], int compPass[], int attPass[], int numYds[], int numTD[] )
{
int i,
p,
k = sizeof(compPass[NUMGAMES]);
FILE *al = fopen("alabama2013.txt","r");
while (fscanf(al ,"%d %d %d %d", &compPass[i], &attPass[i], &numYds[i], &numTD[i]) !=EOF)
{
i++;
}
printf("Number of Games with data: %d\n", i);
for(p=0; p<8 ; p++)
{
printf("%d %d %d %d\n", compPass[p], attPass[p], numYds[p], numTD[p]);
}
return 0;
}
You are already passing in the stat file name, so need to change:
FILE *al = fopen("alabama2013.txt","r");
to
FILE *al = fopen(statFile,"r");
You can do that like this:
#include <stdio.h>
#include <assert.h>
void print_fname(char **farray, int fnum)
{
int i;
assert(farray != NULL);
for (i = 0; i < fnum; ++i) {
assert(farray[i] != NULL);
printf("file name %d: %s\n", i + 1, farray[i]);
}
}
int main()
{
char *farray[] = {"file1", "file2"};
print_fname(farray, 2);
return 0;
}
Hope can help.
This is part of a program where I call a function that reads components from a ".dat" file and save the input to members of a Struct. When I try calling the function from my main.c it gives various errors depending on what I try. Most notably: conflicting types of 'ReadFile' and too few arguments to function 'ReadFile'. I also get a warning "passing argument from 'ReadFile' makes integer from pointer without cast" and some infos.
This is main.c
#include "MyData.h"
#include "NodalA.h"
#include "FileHandling.h"
#include <stdio.h>
#include "windows.h"
int main(){
ComponentType *CircuitData;
int numComp = 6;
int numEl = 0;
int numNodes = 0;
CircuitData = malloc((numComp)*sizeof(ComponentType));
ReadFile(CircuitData, &numEl, &numNodes);
return 0;
}
This is FileHandling.c:
#include "FileHandling.h"
#include "stdio.h"
void ReadFile(ComponentType *CircuitData, int *numEl, int *numNodes){
numEl = 0;
numNodes = 0;
int index = 0;
FILE *data;
data = fopen("mydata.dat", "r");
if (data == NULL){
printf("Error: \"mydata.dat\" could not be opened");
}
else {
while(!feof(data)){
fscanf(data, "%s, %s, %s, %f", CircuitData[index].name, CircuitData[index].node1, CircuitData[index].node2, CircuitData[index].value);
*CircuitData[index].node1 = extractInteger(CircuitData[index].node1);
*CircuitData[index].node2 = extractInteger(CircuitData[index].node2);
if(*CircuitData[index].node1 > *numNodes)
*numNodes = *CircuitData[index].node1;
if(*CircuitData[index].node2 > *numNodes)
*numNodes = *CircuitData[index].node2;
numEl++;
index++;
}
}
fclose(data);
}
And this is MyData.h
#ifndef MYDATA_H_
#define MYDATA_H_
typedef struct Comp{
char name[5]; //Name of circuit component
char node1[5], node2[5]; //2 nodes
float value[5]; //value
}ComponentType;
#endif /* MYDATA_H_ */
Any help would be appreciated. There are more code but I think this is the most important part.
The ReadFile function name used in the program is the same as a ReadFile function in "windows.h". The error "too few arguments to function 'ReadFile'" is most likely caused by the program trying to call the the function from windows with the wrong arguments. Removing "windows.h" or renaming the function ReadFile to something else solves the problem.