c++ memset_memset unsigned char

void * memset ( void * ptr, int value, size_t num );
填充内存块
将ptr指向的内存块的前num个字节设置为指定值（解释为unsigned char）。

• ptr
  Pointer to the block of memory to fill.(指向要填充的内存块的指针。)
• value
  Value to be set. The value is passed as an int, but the function fills the block of memory using the unsigned char conversion of this value.(要设置的值。该值作为int传递，但该函数使用该值的无符号字符转换来填充内存块。)
• num
  Number of bytes to be set to the value.
  size_t is an unsigned integral type.(要设置为值的字节数。
  size_t是无符号整数类型。
  )

/* memset example */
#include <stdio.h>
#include <string.h>

int main ()
{
  char str[] = "almost every programmer should know memset!";
  memset (str,'-',6);
  puts (str);
  return 0;
}

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------ every programmer should know memset!
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