# ErrorRecord
###### tags: `C basics`, `debug`

### sprintf
>致謝
>https://stackoverflow.com/questions/19772667/c-sprintf-array-char-pointers/19772761

sprintf does not allocate memory for the string it writes. You have to provide a valid string for it to write into but are currently passing it an uninitialised pointer.

**it will fail**

int x = 100;
char* string;
sprintf(string,"%d",x);
printf("%s\n",string);

**it works**

int x = 100;
char string[] = "";
sprintf(string,"%d",x);
printf("%s\n",string);

這裡我測試會掛掉喔～～
string size過小

int x = 100;
char string[20];
sprintf(string,"%d",x);
printf("%s\n",string);

x = 100;
char* string = (char*)malloc(sizeof(char)*10);
sprintf(string,"%d",x);
printf("%s\n",string);