Chang was born in Nanjing, the capital of the Republic of China, on 7 November 1929. After the outbreak of the Second Sino-Japanese War, the Japanese army attacked Nanjing in December 1937. Chang's mother fled the city with the children and trekked across China for more than a year, eventually arriving in the wartime capital Chongqing in 1939. His father, who stayed behind to look after his shop, died in the Nanjing Massacre.