Having problems with 2D char arrays - c

Question

So I've got an assignment where my program asks the brand (10 letters), model (10 letters), age (1986 - 2019) and cost (positive real number) of 10 cars and then wants the program to check which car is the oldest and to print out it's brand and model. I don't have a problem with the first part but with the second part.
The code is:
//First part
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define C 10
#define M 11
int main(void)
{
char brand[C][M];
char model[C][M];
int year[C];
float cost[C];
int i, len1, len2, min;
for(i=0; i<C; i++){
printf("Car %d\n", i+1);
do{
printf("Brand: ");
scanf("%s", brand[i]);
len1 = strlen(brand[i]);
} while(len1<0 || len1>10);
do{
printf("Model: ");
scanf("%s", model[i]);
len2 = strlen(model[i]);
} while(len2<0 || len2>10);
do{
printf("Year: ");
scanf("%d", &year[i]);
} while(year[i]<1986 || year[i]>2019);
do{
printf("Cost: ");
scanf("%d", &cost[i]);
} while(cost[i]<=0);
}
//Second part
year[0] = min;
for(i=0; i<10; i++)
if(year[i] < min){
min = year[i];
printf("\nThe oldest car is %s %s\n", brand[i], model[i]);
}
For some reason it either prints out gibberish in the place of brand[i] or if I lose the columns of the if statement prints out all the car brands and their models, where I only want the oldest one.

Answer 1

Aside from scanf not being recommended there are some problems with this code, first when you read the brand and model you do:
do{
printf("Brand: ");
scanf("%s", brand[i]);
len1 = strlen(brand[i]);
} while(len1<0 || len1>10);
The problem here is that you first write the string to brand[i] and then check if it's too long, but you have already written it into the array so if the string is longer than your space you already have a buffer overflow. Limit the size you can read with scanf using scanf("%10s, brand[i]) or better yet use fgets(brand[i], sizeof(brand[i]), stdin).
Next in the second part you use min without initializing it, and you overwrite the content of year[0] with it. You probably wanted something like:
min = 2020; // or a number that will be bigger than all your cars anyway
int older = 0;
i = 0;
for(i=0; i<C; i++){ // Use C here, you have it might as well use it instead of magic numbers
if(year[i] < min){
older = i;
min = year[i];
}
}
printf("\nThe oldest car is %s %s\n", brand[older], model[older]);
but bare in mind that this solution will print multiple cars if they are the oldest ones and have the same year