sprintf cause my program stop working in keil - c

Question

This is my main function and I don't know why when I simulate it in proteos I figured that the code runs up to sprintf and next lines doesn't run and when I comment it the "salam" printed on lcd
I use mingw compiler and I have installed all librarys
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
/* USER CODE BEGIN 2 */
char q[5] = "salam" ;
int a = 6541;
//float b = a/7;
LCD1602_Begin8BIT(RS_GPIO_Port,RS_Pin,E_Pin,D0_GPIO_Port,D0_Pin,D1_Pin,D2_Pin,D3_Pin,D4_GPIO_Port,D4_
Pin,D5_Pin,D6_Pin,D7_Pin);
LCD1602_setCursor(1,1);
//snprintf(q, 20, "%10d", 1234567);
//LCDCHAR_Puts(0, 0, q);
//char command1[50], command2[50]; // Added
//char *temp[] = {NULL, command1, command2, NULL}; // Modified
//temp[0]="sum";
LCD1602_print("mahdi kahrizi");
LCD1602_2ndLine();
sprintf(q,"%d",a);
LCD1602_print(q);

Answer 1

the problem starts from here.
char q[5] = "salam" ;
q is too short to store this word. It has to be at least 6 chars long.
It is Undefined Behaviour as you write outside the array bounds.
When you change the length of the q to be longer
snprintf(q, sizeof(q), "%d", a);