最后一个 printf 语句被跳过

Question

插入所有值后，我期望最终的 printf 语句给出方程的最终结果

#include <stdio.h>
#include <stdlib.h>

int main(void) 
{
    char *carModel; 
    float tankRange; 
    float gasCost; 
    float costTank; 
    float gallonsTank; //gallons in full tank
    float mpg; //miles per gallon
    float costMile;

    carModel = malloc(256);

    printf("What is the model of car? " );
    scanf("%255s", &carModel);  // Don't read more than 255 chars
    printf("How many miles can be driven on a full tank? " );
    scanf("%f", &tankRange);
    printf("What is the gas cost per gallon? " );
    scanf("%f", &gasCost);
    printf("How much does it cost to fill the tank? " );
    scanf("%f", &costTank);
    gallonsTank = costTank / gasCost;
    mpg = tankRange / gallonsTank;
    costMile = mpg / gasCost;
    printf("Amazing! %255s has an mpg of %.3f per gallon! You spent $%.2f to drive one mile!\n",  carModel, mpg, costMile);

return 0;

}

除了最后一个 printf 语句外，所有内容都打印并运行良好，这表明代码已完成运行

Answer 1

scanf的这个调用是不正确的

printf("What is the model of car? " );
scanf("%255s", &carModel);  // Don't read more than 255 chars
               ^^^^^^^^^ 

相反你必须写

printf("What is the model of car? " );
scanf("%255s", carModel);  // Don't read more than 255 chars

否则调用会scanf覆盖局部变量占用的内存。

s当您传递类型的参数时，转换说明符需要char *一个 类型的参数char **。

如果你想输入一个包含多个单词的字符串，那么你可以这样写

printf("What is the model of car? " );
scanf("%255[^\n]", carModel);  // Don't read more than 255 chars

请注意，应在程序结束时释放分配的内存

free( carModel );