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POHow to find & remove memory leaks and errors in my C program after checked it with Valgrind
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copied!<p>After checked my code with Valgrind, it shows a lot of error messages and information and I am not sure about how to find and remove the errors in code?</p> <p>My source code is as follows.</p> <p><strong>myheader.h</strong></p> <pre><code> #include<stdlib.h> #define MAX 15 typedef enum { METROPOLITAN_AREA, TOURIST_AREA, }area_type_t; typedef struct { int population; int area; }metropolitan_t; typedef struct { char *type_place; char *near_airport; }tourist_t; typedef struct { char *name; char *country; area_type_t area_t; union { metropolitan_t metro; tourist_t tourist; }u; }*place_t; extern void get_input(place_t); </code></pre> <p><strong>getinput.c</strong></p> <pre><code>#include<myheader.h> void get_input(place_t place) { int check=1; int num,i,ch; printf("\nEnter the no of records : \n"); scanf("%d",&num); place=(place_t)malloc(sizeof(place_t)*num); if(NULL==place) { printf("\nMemory allocation failed\n"); exit(1); } for(i=0;i<num;i++) { printf("\nEnter the place name : "); place->name=(char *)malloc(sizeof(char)*MAX); if(NULL==place->name) { free(place); printf("\nMemory allocation failed\n"); exit(1); } scanf("%s",place->name); printf("\nEnter the coutry name : "); place->country=(char *)malloc(sizeof(char)*MAX); if(NULL==place->country) { free(place); free(place->name); printf("Memory allocation failed\n"); exit(1); } scanf("%s",place->country); printf("\nPlease Enter '0' if the place is Metropolitan, '1' if the place Tourist place\n"); scanf("%d",&ch); while(check) { switch(ch) { case 0: check=0; place->area_t=METROPOLITAN_AREA; break; case 1: check=0; place->area_t=TOURIST_AREA; break; default: printf("\nPlease enter valid choice \n"); } } if(place->area_t==METROPOLITAN_AREA) { printf("\nEnter the population of the place : "); scanf("%d",&(place->u.metro.population)); printf("\nEnter the area of place :"); scanf("%d",&(place->u.metro.area)); } else { printf("\nEnter the nearest airport name : "); place->u.tourist.near_airport=(char *)malloc(sizeof(char)*MAX); if(NULL==place->u.tourist.near_airport) { printf("Memory allocation failed\n"); exit(1); } scanf("%s",(place->u.tourist.near_airport)); printf("\nEnter the type of tourist spot : "); place->u.tourist.type_place=(char *)malloc(sizeof(char)*MAX); if(NULL==place->u.tourist.type_place) { printf("Memory allocation failed\n"); exit(1); } scanf("%s",(place->u.tourist.type_place)); } check=1; place++; } } </code></pre> <p><strong>main.c</strong></p> <pre><code>#include"myheader.h" int main() { place_t place; get_input(place); return 0; } </code></pre> <p><strong>Command-line transcript</strong></p> <pre class="lang-none prettyprint-override"><code> bash-3.00$ valgrind --tool=memcheck --leak-check=yes --show-reachable=yes a.out ==13514== Memcheck, a memory error detector. ==13514== Copyright (C) 2002-2005, and GNU GPL'd, by Julian Seward et al. ==13514== Using LibVEX rev 1575, a library for dynamic binary translation. ==13514== Copyright (C) 2004-2005, and GNU GPL'd, by OpenWorks LLP. ==13514== Using valgrind-3.1.1, a dynamic binary instrumentation framework. ==13514== Copyright (C) 2000-2005, and GNU GPL'd, by Julian Seward et al. ==13514== For more details, rerun with: -v ==13514== Enter the no of records : 2 Enter the place name : Banglore Enter the coutry name : India Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place 0 ==13514== Invalid write of size 4 ==13514== at 0x400789: get_input (getinput.c:43) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x400637: get_input (getinput.c:8) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid read of size 4 ==13514== at 0x4007BB: get_input (getinput.c:53) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D040 is 0 bytes after a block of size 16 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x400637: get_input (getinput.c:8) ==13514== by 0x4005E8: main (main.c:5) Enter the population of the place : 303030 Enter the area of place :2500 ==13514== ==13514== Invalid write of size 8 ==13514== at 0x40068C: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd ==13514== ==13514== Invalid read of size 8 ==13514== at 0x400693: get_input (getinput.c:18) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd ==13514== ==13514== Invalid read of size 8 ==13514== at 0x4006BF: get_input (getinput.c:24) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D058 is not stack'd, malloc'd or (recently) free'd Enter the place name : London ==13514== ==13514== Invalid write of size 8 ==13514== at 0x4006EE: get_input (getinput.c:26) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid read of size 8 ==13514== at 0x4006F6: get_input (getinput.c:27) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid read of size 8 ==13514== at 0x4006F6: get_input (getinput.c:27) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid read of size 8 ==13514== at 0x40072F: get_input (getinput.c:34) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D060 is 16 bytes before a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) Enter the coutry name : London Please Enter '0' if the place is Metropolitan, '1' if the place Tourist place 1 ==13514== ==13514== Invalid write of size 4 ==13514== at 0x40079D: get_input (getinput.c:47) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D068 is 8 bytes before a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid write of size 8 ==13514== at 0x40082F: get_input (getinput.c:62) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid read of size 8 ==13514== at 0x400837: get_input (getinput.c:63) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== Invalid read of size 8 ==13514== at 0x40085B: get_input (getinput.c:68) ==13514== by 0x4005E8: main (main.c:5) ==13514== Address 0x4A2D078 is 8 bytes inside a block of size 15 alloc'd ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) Enter the nearest airport name : London Enter the type of tourist spot : Entertainment ==13514== ==13514== ERROR SUMMARY: 13 errors from 12 contexts (suppressed: 4 from 1) ==13514== malloc/free: in use at exit: 106 bytes in 7 blocks. ==13514== malloc/free: 7 allocs, 0 frees, 106 bytes allocated. ==13514== For counts of detected errors, rerun with: -v ==13514== searching for pointers to 7 not-freed blocks. ==13514== checked 75,768 bytes. ==13514== ==13514== ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 1 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40088A: get_input (getinput.c:70) ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40088A: get_input (getinput.c:70) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== ==13514== 15 bytes in 1 blocks are definitely lost in loss record 2 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40082E: get_input (getinput.c:62) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== ==13514== 15 bytes in 1 blocks are definitely lost in loss record 3 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x4006ED: get_input (getinput.c:26) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== ==13514== 15 bytes in 1 blocks are definitely lost in loss record 4 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 5 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x4006ED: get_input (getinput.c:26) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== ==13514== 15 bytes in 1 blocks are indirectly lost in loss record 6 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x40068B: get_input (getinput.c:17) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== ==13514== ==13514== 61 (16 direct, 45 indirect) bytes in 1 blocks are definitely lost in loss record 7 of 7 ==13514== at 0x4904A06: malloc (vg_replace_malloc.c:149) ==13514== by 0x400637: get_input (getinput.c:8) ==13514== by 0x4005E8: main (main.c:5) ==13514== ==13514== LEAK SUMMARY: ==13514== definitely lost: 61 bytes in 4 blocks. ==13514== indirectly lost: 45 bytes in 3 blocks. ==13514== possibly lost: 0 bytes in 0 blocks. ==13514== still reachable: 0 bytes in 0 blocks. ==13514== suppressed: 0 bytes in 0 blocks. </code></pre> <p>How can I resolve this and make my program more memory-efficient? Is there anything wrong in the <code>malloc()</code> statements that I used?</p>

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