1. Assigning value using a pointer:
```C
#include <stdio.h>
struct mystruct {
float x;
double dx;
};
int main() {
struct mystruct var, *pvar;
pvar = &var;
pvar->dx = 3.141592; // Assigning the value 3.141592 to field dx using the pointer
return 0;
}
```
In this code, we define a structure `mystruct` with `float x` and `double dx` fields. We create a variable `var` of type `mystruct` and a pointer `pvar` of type `mystruct*`. Then, we assign the address of `var` to `pvar` using the address-of operator `&`. Finally, we use the pointer syntax `pvar->dx` to assign the value 3.141592 to the `dx` field of `var` without directly using `var`.
2. Reading the second-to-the-last value from a file:
```C
#include <stdio.h>
int main() {
FILE *pf;
float x;
int count = 0;
pf = fopen("my.dat", "rb");
if (pf == NULL) {
printf("Error opening the file.\\");
return 1;
}
// Seek to the end of the file and check its size
fseek(pf, 0, SEEK_END);
long size = ftell(pf);
// Read the second-to-the-last float value
fseek(pf, size - sizeof(float) * 2, SEEK_SET);
fread(&x, sizeof(float), 1, pf);
fclose(pf);
printf("Second-to-the-last value: %.2f\\", x);
return 0;
}
```
In this code, we open the file "my.dat" in binary mode for reading. We first check if the file was successfully opened. Then, we seek to the end of the file using `fseek` and determine its size using `ftell`. With the file size, we can calculate the position of the second-to-the-last float value by seeking back from the end by `sizeof(float) * 2`. Finally, we read the float value using `fread` and print it.
3. Generating pseudo-random values using rand():
```C
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main() {
int y[400], i;
// Set seed for random number generation
srand(time(NULL));
// Generate pseudo-random values between 6 and 64
for (i = 0; i < 400; i++) {
y[i] = rand() % 59 + 6;
}
// Print the generated values
for (i = 0; i < 400; i++) {
printf("%d ", y[i]);
}
return 0;
}
```
In this code, we first set the seed for the random number generation using `srand` and `time`. Then, we use a loop to generate 400 pseudo-random values between 6 and 64 (inclusive) using `rand() % 59 + 6`. Finally, we print the generated values using another loop.
Please note that these code snippets are provided as guidance and may require further modifications based on your specific requirements.