数制转换

十进制数N与其他d进制的转换一个简单的算法是：
N = (N/d)*d + N%d
对应代码：

int num;
while(num){
    item = num % d;
    stack->push(d);
    num /= d;
}

最后将栈内的数从栈顶到栈底输出即为转换后的进制数。

NumberConversion.c利用了前面的C封装的顺序栈对象 用线性表表示的顺序栈
实现了输入一个十六进制/十进制/八进制/二进制的正数/负数，输出十六进制/十进制/八进制/二进制对应的数值，达到数制转换的效果。
github源码

NumberConversion.c文件

#include <stdio.h>
#include <malloc.h>
#include "LinearListStack.h"

int strlen(char *str){
    int i = 0;
    while(*(str+i) != '\0'){
        i++;
    }
    return i;
}

double my_pow(double a,int b){
    int s = 0,i;
    double r = 1;
    if(b == 0) return 1;
    if(b<0){
        b*=-1;
        s = 1;
    }
    for(i = 0; i < b; i++){
        r *= a;
    }
    if(s) r = 1/r;
    return r;
}

LinearListStack *intToHex(int num){
    LinearListStack *stack = InitLinearListStack();
    char item;
    if(num < 0){
        num = -num;
    }else if(num == 0){
        item = 0x30;
        stack->push(stack,&item);
    }
    while(num){
        item = num % 16;
        if(item <= 9){
            item += 0x30;
        }else{
            item += 0x37;
        }
        stack->push(stack,&item);
        num /= 16;
    }
    return stack;
}

LinearListStack *intToDec(int num){
    LinearListStack *stack = InitLinearListStack();
    char item;
    if(num < 0){
        num = -num;
    }else if(num == 0){
        item = 0x30;
        stack->push(stack,&item);
    }
    while(num){
        item = num % 10;
        item += 0x30;
        stack->push(stack,&item);
        num /= 10;
    }
    return stack;
}

LinearListStack *intToOct(int num){
    LinearListStack *stack = InitLinearListStack();
    char item;
    if(num < 0){
        num = -num;
    }else if(num == 0){
        item = 0x30;
        stack->push(stack,&item);
    }
    while(num){
        item = num % 8;
        item += 0x30;
        stack->push(stack,&item);
        num /= 8;
    }
    return stack;
}

LinearListStack *intToBin(int num){
    LinearListStack *stack = InitLinearListStack();
    char item;
    if(num < 0){
        num = -num;
    }else if(num == 0){
        item = 0x30;
        stack->push(stack,&item);
    }
    while(num){
        item = num % 2;
        item += 0x30;
        stack->push(stack,&item);
        num /= 2;
    }
    return stack;
}

void displayConvert(int num){
    int negative = 0;
    LinearListStack *stack = NULL;;
    negative = num < 0 ? 1 : 0;
    stack = intToDec(num);
    negative ? printf("DEC: -") : printf("DEC: ");
    stack->downPrint(stack);
    DestroyLinearListStack(stack);
    stack = intToHex(num);
    negative ? printf("HEX: -0X") : printf("HEX: 0X");
    stack->downPrint(stack);
    DestroyLinearListStack(stack);
    if(negative){
        stack = intToHex(0XFFFF + num + 1);
        printf("HEX negative number saved form: 0X");
        stack->downPrint(stack);
    }
    DestroyLinearListStack(stack);
    stack = intToOct(num);
    negative ? printf("OCT: -o") : printf("OCT: o");
    stack->downPrint(stack);
    DestroyLinearListStack(stack);
        if(negative){
        stack = intToOct(0XFFFF + num + 1);
        printf("OCT negative number saved form: o");
        stack->downPrint(stack);
    }
    DestroyLinearListStack(stack);
    stack = intToBin(num);
    negative ? printf("BIN: -b") : printf("BIN: b");
    stack->downPrint(stack);
    DestroyLinearListStack(stack);
    if(negative){
        stack = intToBin(0XFFFF + num + 1);
        printf("BIN negative number saved form: b");
        stack->downPrint(stack);
    }
    DestroyLinearListStack(stack);
}

int stringToInt(char *str){
    int basenum = 0,i = 0,num = 0;
    int stack_length = 0;
    int start_save = 0;
    int negative = 0;
    char item;
    LinearListStack *stack = InitLinearListStack();
    while(*str != '\0'){
        if(start_save != 1){
            if(*str == '-'){
                negative = 1;
            }else if(*str == 'o' || *str == 'O'){
                start_save = 1;
                basenum = 8;
            }else if(*str == 'b' || *str == 'B'){
                start_save = 1;
                basenum = 2;
            }else if(*str == 'd' || *str == 'D'){
                start_save = 1;
                basenum = 10;
            }else if(*str == 'x' || *str == 'X'){
                if(start_save == 2){
                    start_save = 1;
                    basenum = 16;
                }
            }else if(*str == '0'){
                start_save = 2;
            }
        }else if(start_save == 1){
            stack->push(stack,str);
        }
        str++;
    }
    stack_length = stack->length(stack);
    for(i=0;i<stack_length;i++){
        stack->pop(stack,&item);
        if(item >= 0x30 && item <= 0x39){
            item -= 0x30;
        }else if(item >= 0x41 && item <= 0x46){
            if(basenum == 16){
                item -= 0x37;
            }else{
                printf("Num string formal error!\n");
                DestroyLinearListStack(stack);
                return 0;
            }
        }else if(item >= 0x61 && item <= 0x66){
            if(basenum == 16){
                item -= 0x57;
            }else{
                printf("Num string formal error!\n");
                DestroyLinearListStack(stack);
                return 0;
            }
        }else{
                printf("Num string formal error!\n");
                DestroyLinearListStack(stack);
                return 0;
        }
        num += my_pow(basenum,i)*item;
    }
    DestroyLinearListStack(stack);
    if(negative) num = -num;
    return num;
}

int main(void)
{
    int num;
    char str[100];
    printf("please enter a num!\n");
    printf("num format just like these:\n");
    printf("HEX: -0X1F -0x1F 0x1F 0X1F\n");
    printf("DEC: -D11 -d11 D11 d11\n");
    printf("OCT: -O11 -o11 O11 o11\n");
    printf("BIN: -B10 -b10 B10 b10\n");
    printf("Enter:\n");
    gets(str);
    printf("\n");
    num = stringToInt(str);
    displayConvert(num);
    return 0;
}

编译：

gcc LinearListStack.c LinearListStack.h NumberConversion.c -o NumberConversion

运行NumberConversion,显示：

please enter a num!
num format just like these:
HEX: -0X1F -0x1F 0x1F 0X1F
DEC: -D11 -d11 D11 d11
OCT: -O11 -o11 O11 o11
BIN: -B10 -b10 B10 b10
Enter:

例1：
输入：d123
输出：

DEC: 123
HEX: 0X7B
OCT: o173
BIN: b1111011

例2：
输入：-0x2df3
输出：

DEC: -11763
HEX: -0X2DF3
HEX negative number saved form: 0XD20D
OCT: -o26763
OCT negative number saved form: o151015
BIN: -b10110111110011
BIN negative number saved form: b1101001000001101