移位操作：因为操作符的原因，注意加括号。还有没必要在移位的时候进行（uint32_t）转换。

测试程序如下： 

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
 
int main()
{
	uint8_t buffer[4] = {0x11, 0x22, 0x33, 0x44};
    uint32_t value = buffer[0] + (buffer[1] << 8) + (buffer[2] << 16) + (buffer[3] << 24);

	printf("value = %x\n", value);

	return 0;
}

 

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
 
int main()
{
	uint8_t buffer[4] = {0x11, 0x22, 0x33, 0x44};
    uint32_t value = buffer[0] + buffer[1] << 8 + buffer[2] << 16 + buffer[3] << 24;

	printf("value = %x\n", value);

	return 0;
}