C语言实现数字转换为罗马数字

const int value[]={1000,900,500,400,100,90,50,40,10,9,5,4,1};
const char* symbol[]={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
char * intToRoman(int num){
    char* roman=(char*)malloc(sizeof(char)*16);
    roman[0]='\0';
    for(int i=0;i<13;i++){
        while(num>=value[i]){
            num-=value[i];
            strcpy(roman+strlen(roman),symbol[i]);
        }
        if(num==0){
            break;
        }
    }
    return roman;
}

?学会了吗？
关于罗马数字的编码规则，value表中的值与罗马符号一一对应。当I,X,C在左侧时表示减去对应的值。I=1,X=10,C=100.