### Ejemplo
```c
#include
#include
char *printLocalTime()
{
char *timeStringBuff=malloc(30); //50 chars should be enough
//char timeStringBuff[100]; //50 chars should be enough
char *mic = "2022";
char c = 'm';
int test = 1;
char prueba[50]; char *prueba_m = malloc(50);
printf("%d\n",sizeof(prueba));
printf("%d\n",sizeof(prueba_m));
sprintf(timeStringBuff, "they tried everything %s %d\n",mic,test);
//Optional: Construct String object
// Esto retorna un puntero a la direccion de memoria en donde esta timeStringBuff
// *timeStringBuff = timeStringBuff[0]
// *(timeStringBuff+3) = timeStringBuff[3]
printf("%s\n",timeStringBuff);
// Vos no retornas la palabra cuando ejecutas return timeStringBufff retornas un puntero
// que apunta a la primer letra del char. Y lo que hace el '%s' es leer hasta que encuentra el \0
printf("%c\n",*timeStringBuff);
char hola[] = {'h','o','l','a','\0'};
printf("%s\n",hola);
// Cambio valor
for(int i=0; i<10000; i++){
sprintf(timeStringBuff, "reincarnation");
}
printf("%s\n",timeStringBuff);
if (c == 'm') printf("we're winning\n");
return timeStringBuff;
}
int main()
{
char *freeThis = printLocalTime();
printf("%s\n",freeThis);
free(freeThis);
printf("%s\n",freeThis);
int a = 65;
printf("%c\n",(char)a);
return 0;
}
```
#### Uniones
```c
union Data{
int i;
float f;
char str[20];
};
union Data data;
data.i = 10;
data.f = 220.5;
strcpy(data.str, "C Programming");
}
```
### FILE OPENING:
```c
int main()
{
FILE* filePointer;
char dataToBeWritten[50] = "GeeksforGeeks-A Computer "
"Science Portal for Geeks";
filePointer = fopen("GfgTest.c", "w");
if (filePointer == NULL) {
printf("GfgTest.c file failed to open.");
}
else {
printf("The file is now opened.\n");
if (strlen(dataToBeWritten) > 0) {
fputs(dataToBeWritten, filePointer);
fputs("\n", filePointer);
}
/*
while (fgets(dataToBeRead, 50, filePointer)
!= NULL) {
// Print the dataToBeRead
printf("%s", dataToBeRead);
}
*/
fclose(filePointer);
printf("Data successfully written in file "
"GfgTest.c\n");
printf("The file is now closed.");
}
return 0;
}
```